--- a/wp-includes/wp-db.php
+++ b/wp-includes/wp-db.php
@@ -140,6 +140,43 @@
 	protected $result;
 
 	/**
+	 * Cached column info, for sanity checking data before inserting
+	 *
+	 * @since 4.2.0
+	 * @access protected
+	 * @var array
+	 */
+	protected $col_meta = array();
+
+	/**
+	 * Calculated character sets on tables
+	 *
+	 * @since 4.2.0
+	 * @access protected
+	 * @var array
+	 */
+	protected $table_charset = array();
+
+	/**
+	 * Whether text fields in the current query need to be sanity checked.
+	 *
+	 * @since 4.2.0
+	 * @access protected
+	 * @var bool
+	 */
+	protected $check_current_query = true;
+
+	/**
+	 * Flag to ensure we don't run into recursion problems when checking the collation.
+	 *
+	 * @since 4.2.0
+	 * @access private
+	 * @see wpdb::check_safe_collation()
+	 * @var boolean
+	 */
+	private $checking_collation = false;
+
+	/**
 	 * Saved info on the table column
 	 *
 	 * @since 0.71
@@ -575,6 +612,14 @@
 	 * @param mixed  $value The value to set
 	 */
 	function __set( $name, $value ) {
+		$protected_members = array(
+			'col_meta',
+			'table_charset',
+			'check_current_query',
+		);
+		if (  in_array( $name, $protected_members, true ) ) {
+			return;
+		}
 		$this->$name = $value;
 	}
 
@@ -1178,8 +1223,10 @@
 	 * @return int|false Number of rows affected/selected or false on error
 	 */
 	function query( $query ) {
-		if ( ! $this->ready )
+		if ( ! $this->ready ) {
+			$this->check_current_query = true;
 			return false;
+        }
 
 		// some queries are made before the plugins have been loaded, and thus cannot be filtered with this method
 		$query = apply_filters( 'query', $query );
@@ -1190,6 +1237,19 @@
 		// Log how the function was called
 		$this->func_call = "\$db->query(\"$query\")";
 
+		// If we're writing to the database, make sure the query will write safely.
+		if ( $this->check_current_query && ! $this->check_ascii( $query ) ) {
+			$stripped_query = $this->strip_invalid_text_from_query( $query );
+			// strip_invalid_text_from_query() can perform queries, so we need
+			// to flush again, just to make sure everything is clear.
+			$this->flush();
+			if ( $stripped_query !== $query ) {
+				$this->insert_id = 0;
+				return false;
+			}
+		}
+
+		$this->check_current_query = true;
 		// Keep track of the last query for debug..
 		$this->last_query = $query;
 
@@ -1303,23 +1363,29 @@
 	 * @return int|false The number of rows affected, or false on error.
 	 */
 	function _insert_replace_helper( $table, $data, $format = null, $type = 'INSERT' ) {
-		if ( ! in_array( strtoupper( $type ), array( 'REPLACE', 'INSERT' ) ) )
+		if ( ! in_array( strtoupper( $type ), array( 'REPLACE', 'INSERT' ) ) ) {
+			return false;
+		}
+
+		$data = $this->process_fields( $table, $data, $format );
+		if ( false === $data ) {
 			return false;
-		$this->insert_id = 0;
-		$formats = $format = (array) $format;
-		$fields = array_keys( $data );
-		$formatted_fields = array();
-		foreach ( $fields as $field ) {
-			if ( !empty( $format ) )
-				$form = ( $form = array_shift( $formats ) ) ? $form : $format[0];
-			elseif ( isset( $this->field_types[$field] ) )
-				$form = $this->field_types[$field];
-			else
-				$form = '%s';
-			$formatted_fields[] = $form;
 		}
-		$sql = "{$type} INTO `$table` (`" . implode( '`,`', $fields ) . "`) VALUES (" . implode( ",", $formatted_fields ) . ")";
-		return $this->query( $this->prepare( $sql, $data ) );
+
+		$formats = $values = array();
+		foreach ( $data as $value ) {
+			$formats[] = $value['format'];
+			$values[]  = $value['value'];
+		}
+
+		$fields  = '`' . implode( '`, `', array_keys( $data ) ) . '`';
+		$formats = implode( ', ', $formats );
+
+		$sql = "$type INTO `$table` ($fields) VALUES ($formats)";
+
+		$this->insert_id = 0;
+		$this->check_current_query = false;
+		return $this->query( $this->prepare( $sql, $values ) );
 	}
 
 	/**
@@ -1344,34 +1410,36 @@
 	 * @return int|false The number of rows updated, or false on error.
 	 */
 	function update( $table, $data, $where, $format = null, $where_format = null ) {
-		if ( ! is_array( $data ) || ! is_array( $where ) )
+		if ( ! is_array( $data ) || ! is_array( $where ) ) {
 			return false;
+        }
 
-		$formats = $format = (array) $format;
-		$bits = $wheres = array();
-		foreach ( (array) array_keys( $data ) as $field ) {
-			if ( !empty( $format ) )
-				$form = ( $form = array_shift( $formats ) ) ? $form : $format[0];
-			elseif ( isset($this->field_types[$field]) )
-				$form = $this->field_types[$field];
-			else
-				$form = '%s';
-			$bits[] = "`$field` = {$form}";
+		$data = $this->process_fields( $table, $data, $format );
+		if ( false === $data ) {
+			return false;
+		}
+		$where = $this->process_fields( $table, $where, $where_format );
+		if ( false === $where ) {
+			return false;
 		}
 
-		$where_formats = $where_format = (array) $where_format;
-		foreach ( (array) array_keys( $where ) as $field ) {
-			if ( !empty( $where_format ) )
-				$form = ( $form = array_shift( $where_formats ) ) ? $form : $where_format[0];
-			elseif ( isset( $this->field_types[$field] ) )
-				$form = $this->field_types[$field];
-			else
-				$form = '%s';
-			$wheres[] = "`$field` = {$form}";
+		$fields = $conditions = $values = array();
+		foreach ( $data as $field => $value ) {
+			$fields[] = "`$field` = " . $value['format'];
+			$values[] = $value['value'];
 		}
+		foreach ( $where as $field => $value ) {
+			$conditions[] = "`$field` = " . $value['format'];
+			$values[] = $value['value'];
+		}
+
+		$fields = implode( ', ', $fields );
+		$conditions = implode( ' AND ', $conditions );
 
-		$sql = "UPDATE `$table` SET " . implode( ', ', $bits ) . ' WHERE ' . implode( ' AND ', $wheres );
-		return $this->query( $this->prepare( $sql, array_merge( array_values( $data ), array_values( $where ) ) ) );
+		$sql = "UPDATE `$table` SET $fields WHERE $conditions";
+
+		$this->check_current_query = false;
+		return $this->query( $this->prepare( $sql, $values ) );
 	}
 
 	/**
@@ -1393,27 +1461,134 @@
 	 * @return int|false The number of rows updated, or false on error.
 	 */
 	function delete( $table, $where, $where_format = null ) {
-		if ( ! is_array( $where ) )
+		if ( ! is_array( $where ) ) {
 			return false;
+        }
 
-		$bits = $wheres = array();
+		$where = $this->process_fields( $table, $where, $where_format );
+		if ( false === $where ) {
+			return false;
+		}
 
-		$where_formats = $where_format = (array) $where_format;
 
-		foreach ( array_keys( $where ) as $field ) {
-			if ( !empty( $where_format ) ) {
-				$form = ( $form = array_shift( $where_formats ) ) ? $form : $where_format[0];
+		$conditions = $values = array();
+		foreach ( $where as $field => $value ) {
+			$conditions[] = "`$field` = " . $value['format'];
+			$values[] = $value['value'];
+		}
+
+		$conditions = implode( ' AND ', $conditions );
+
+		$sql = "DELETE FROM `$table` WHERE $conditions";
+
+		$this->check_current_query = false;
+		return $this->query( $this->prepare( $sql, $values ) );
+	}
+
+
+	/**
+	 * Processes arrays of field/value pairs and field formats.
+	 *
+	 * This is a helper method for wpdb's CRUD methods, which take field/value
+	 * pairs for inserts, updates, and where clauses. This method first pairs
+	 * each value with a format. Then it determines the charset of that field,
+	 * using that to determine if any invalid text would be stripped. If text is
+	 * stripped, then field processing is rejected and the query fails.
+	 *
+	 * @since 4.2.0
+	 * @access protected
+	 *
+	 * @param string $table  Table name.
+	 * @param array  $data   Field/value pair.
+	 * @param mixed  $format Format for each field.
+	 * @return array|bool Returns an array of fields that contain paired values
+	 *                    and formats. Returns false for invalid values.
+	 */
+	protected function process_fields( $table, $data, $format ) {
+		$data = $this->process_field_formats( $data, $format );
+		$data = $this->process_field_charsets( $data, $table );
+		if ( false === $data ) {
+			return false;
+		}
+
+		$converted_data = $this->strip_invalid_text( $data );
+
+		if ( $data !== $converted_data ) {
+			return false;
+		}
+		return $data;
+	}
+
+
+	/**
+	 * Prepares arrays of value/format pairs as passed to wpdb CRUD methods.
+	 *
+	 * @since 4.2.0
+	 * @access protected
+	 *
+	 * @param array $data   Array of fields to values.
+	 * @param mixed $format Formats to be mapped to the values in $data.
+	 * @return array Array, keyed by field names with values being an array
+	 *               of 'value' and 'format' keys.
+	 */
+	protected function process_field_formats( $data, $format ) {
+		$formats = $original_formats = (array) $format;
+
+		foreach ( $data as $field => $value ) {
+			$value = array(
+				'value'  => $value,
+				'format' => '%s',
+			);
+
+			if ( ! empty( $format ) ) {
+				$value['format'] = array_shift( $formats );
+				if ( ! $value['format'] ) {
+					$value['format'] = reset( $original_formats );
+				}
 			} elseif ( isset( $this->field_types[ $field ] ) ) {
-				$form = $this->field_types[ $field ];
+				$value['format'] = $this->field_types[ $field ];
+			}
+
+			$data[ $field ] = $value;
+		}
+
+		return $data;
+	}
+
+	/**
+	 * Adds field charsets to field/value/format arrays generated by
+	 * the {@see wpdb::process_field_formats()} method.
+	 *
+	 * @since 4.2.0
+	 * @access protected
+	 *
+	 * @param array  $data  As it comes from the {@see wpdb::process_field_formats()} method.
+	 * @param string $table Table name.
+	 * @return The same array as $data with additional 'charset' keys.
+	 */
+	protected function process_field_charsets( $data, $table ) {
+		foreach ( $data as $field => $value ) {
+			if ( '%d' === $value['format'] || '%f' === $value['format'] ) {
+				// We can skip this field if we know it isn't a string.
+				// This checks %d/%f versus ! %s because it's sprintf() could take more.
+				$value['charset'] = false;
+			} elseif ( $this->check_ascii( $value['value'] ) ) {
+				// If it's ASCII, then we don't need the charset. We can skip this field.
+				$value['charset'] = false;
 			} else {
-				$form = '%s';
+				$value['charset'] = $this->get_col_charset( $table, $field );
+				if ( is_wp_error( $value['charset'] ) ) {
+					return false;
+				}
+
+				// This isn't ASCII. Don't have strip_invalid_text() re-check.
+				$value['ascii'] = false;
 			}
 
-			$wheres[] = "$field = $form";
+			$data[ $field ] = $value;
 		}
 
-		$sql = "DELETE FROM $table WHERE " . implode( ' AND ', $wheres );
-		return $this->query( $this->prepare( $sql, $where ) );
+        return $data;
 	}
 
 
@@ -1433,6 +1608,11 @@
 	 */
 	function get_var( $query = null, $x = 0, $y = 0 ) {
 		$this->func_call = "\$db->get_var(\"$query\", $x, $y)";
+
+		if ( $this->check_safe_collation( $query ) ) {
+			$this->check_current_query = false;
+		}
+
 		if ( $query )
 			$this->query( $query );
 
@@ -1460,6 +1640,11 @@
 	 */
 	function get_row( $query = null, $output = OBJECT, $y = 0 ) {
 		$this->func_call = "\$db->get_row(\"$query\",$output,$y)";
+
+		if ( $this->check_safe_collation( $query ) ) {
+			$this->check_current_query = false;
+		}
+
 		if ( $query )
 			$this->query( $query );
 		else
@@ -1493,6 +1678,10 @@
 	 * @return array Database query result. Array indexed from 0 by SQL result row number.
 	 */
 	function get_col( $query = null , $x = 0 ) {
+		if ( $this->check_safe_collation( $query ) ) {
+			$this->check_current_query = false;
+		}
+
 		if ( $query )
 			$this->query( $query );
 
@@ -1520,6 +1709,10 @@
 	function get_results( $query = null, $output = OBJECT ) {
 		$this->func_call = "\$db->get_results(\"$query\", $output)";
 
+		if ( $this->check_safe_collation( $query ) ) {
+			$this->check_current_query = false;
+		}
+
 		if ( $query )
 			$this->query( $query );
 		else
@@ -1558,6 +1751,507 @@
 	}
 
 	/**
+	 * Retrieves the character set for the given table.
+	 *
+	 * @since 4.2.0
+	 * @access protected
+	 *
+	 * @param string $table Table name.
+	 * @return string|WP_Error Table character set, {@see WP_Error} object if it couldn't be found.
+	 */
+	protected function get_table_charset( $table ) {
+		$tablekey = strtolower( $table );
+
+		/**
+		 * Filter the table charset value before the DB is checked.
+		 *
+		 * Passing a non-null value to the filter will effectively short-circuit
+		 * checking the DB for the charset, returning that value instead.
+		 *
+		 * @since 4.2.0
+		 *
+		 * @param string $charset The character set to use. Default null.
+		 * @param string $table   The name of the table being checked.
+		 */
+		$charset = apply_filters( 'pre_get_table_charset', null, $table );
+		if ( null !== $charset ) {
+			return $charset;
+		}
+
+		if ( isset( $this->table_charset[ $tablekey ] ) ) {
+			return $this->table_charset[ $tablekey ];
+		}
+
+		$charsets = $columns = array();
+		$results = $this->get_results( "SHOW FULL COLUMNS FROM `$table`" );
+		if ( ! $results ) {
+			return new WP_Error( 'wpdb_get_table_charset_failure' );
+		}
+
+		foreach ( $results as $column ) {
+			$columns[ strtolower( $column->Field ) ] = $column;
+		}
+
+		$this->col_meta[ $tablekey ] = $columns;
+
+		foreach ( $columns as $column ) {
+			if ( ! empty( $column->Collation ) ) {
+				list( $charset ) = explode( '_', $column->Collation );
+				$charsets[ strtolower( $charset ) ] = true;
+			}
+
+			list( $type ) = explode( '(', $column->Type );
+
+			// A binary/blob means the whole query gets treated like this.
+			if ( in_array( strtoupper( $type ), array( 'BINARY', 'VARBINARY', 'TINYBLOB', 'MEDIUMBLOB', 'BLOB', 'LONGBLOB' ) ) ) {
+				$this->table_charset[ $tablekey ] = 'binary';
+				return 'binary';
+			}
+		}
+
+		// utf8mb3 is an alias for utf8.
+		if ( isset( $charsets['utf8mb3'] ) ) {
+			$charsets['utf8'] = true;
+			unset( $charsets['utf8mb3'] );
+		}
+
+		// Check if we have more than one charset in play.
+		$count = count( $charsets );
+		if ( 1 === $count ) {
+			$charset = key( $charsets );
+		} elseif ( 0 === $count ) {
+			// No charsets, assume this table can store whatever.
+			$charset = false;
+		} else {
+			// More than one charset. Remove latin1 if present and recalculate.
+			unset( $charsets['latin1'] );
+			$count = count( $charsets );
+			if ( 1 === $count ) {
+				// Only one charset (besides latin1).
+				$charset = key( $charsets );
+			} elseif ( 2 === $count && isset( $charsets['utf8'], $charsets['utf8mb4'] ) ) {
+				// Two charsets, but they're utf8 and utf8mb4, use utf8.
+				$charset = 'utf8';
+			} else {
+				// Two mixed character sets. ascii.
+				$charset = 'ascii';
+			}
+		}
+
+		$this->table_charset[ $tablekey ] = $charset;
+		return $charset;
+	}
+
+	/**
+	 * Retrieves the character set for the given column.
+	 *
+	 * @since 4.2.0
+	 * @access public
+	 *
+	 * @param string $table  Table name.
+	 * @param string $column Column name.
+	 * @return mixed Column character set as a string. False if the column has no
+	 *               character set. {@see WP_Error} object if there was an error.
+	 */
+	public function get_col_charset( $table, $column ) {
+		$tablekey = strtolower( $table );
+		$columnkey = strtolower( $column );
+
+		/**
+		 * Filter the column charset value before the DB is checked.
+		 *
+		 * Passing a non-null value to the filter will short-circuit
+		 * checking the DB for the charset, returning that value instead.
+		 *
+		 * @since 4.2.0
+		 *
+		 * @param string $charset The character set to use. Default null.
+		 * @param string $table   The name of the table being checked.
+		 * @param string $column  The name of the column being checked.
+		 */
+		$charset = apply_filters( 'pre_get_col_charset', null, $table, $column );
+		if ( null !== $charset ) {
+			return $charset;
+		}
+
+		// Skip this entirely if this isn't a MySQL database.
+		if ( false === $this->is_mysql ) {
+			return false;
+		}
+
+		if ( empty( $this->table_charset[ $tablekey ] ) ) {
+			// This primes column information for us.
+			$table_charset = $this->get_table_charset( $table );
+			if ( is_wp_error( $table_charset ) ) {
+				return $table_charset;
+			}
+		}
+
+		// If still no column information, return the table charset.
+		if ( empty( $this->col_meta[ $tablekey ] ) ) {
+			return $this->table_charset[ $tablekey ];
+		}
+
+		// If this column doesn't exist, return the table charset.
+		if ( empty( $this->col_meta[ $tablekey ][ $columnkey ] ) ) {
+			return $this->table_charset[ $tablekey ];
+		}
+
+		// Return false when it's not a string column.
+		if ( empty( $this->col_meta[ $tablekey ][ $columnkey ]->Collation ) ) {
+			return false;
+		}
+
+		list( $charset ) = explode( '_', $this->col_meta[ $tablekey ][ $columnkey ]->Collation );
+		return $charset;
+	}
+
+	/**
+	 * Check if a string is ASCII.
+	 *
+	 * The negative regex is faster for non-ASCII strings, as it allows
+	 * the search to finish as soon as it encounters a non-ASCII character.
+	 *
+	 * @since 4.2.0
+	 * @access protected
+	 *
+	 * @param string $string String to check.
+	 * @return bool True if ASCII, false if not.
+	 */
+	protected function check_ascii( $string ) {
+		if ( function_exists( 'mb_check_encoding' ) ) {
+			if ( mb_check_encoding( $string, 'ASCII' ) ) {
+				return true;
+			}
+		} elseif ( ! preg_match( '/[^\x00-\x7F]/', $string ) ) {
+			return true;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Check if the query is accessing a collation considered safe on the current version of MySQL.
+	 *
+	 * @since 4.2.0
+	 * @access protected
+	 *
+	 * @param string $query The query to check.
+	 * @return bool True if the collation is safe, false if it isn't.
+	 */
+	protected function check_safe_collation( $query ) {
+		if ( $this->checking_collation ) {
+			return true;
+		}
+		$table = $this->get_table_from_query( $query );
+		if ( ! $table ) {
+			return false;
+		}
+
+		$this->checking_collation = true;
+		$this->get_table_charset( $table );
+		$this->checking_collation = false;
+
+		$table = strtolower( $table );
+		if ( empty( $this->col_meta[ $table ] ) ) {
+			return false;
+		}
+
+		foreach( $this->col_meta[ $table ] as $col ) {
+			if ( empty( $col->Collation ) ) {
+				continue;
+			}
+
+			if ( ! in_array( $col->Collation, array( 'utf8_general_ci', 'utf8_bin', 'utf8mb4_general_ci', 'utf8mb4_bin' ), true ) ) {
+				return false;
+			}
+		}
+
+		return true;
+	}
+
+	/**
+	 * Strips any invalid characters based on value/charset pairs.
+	 *
+	 * @since 4.2.0
+	 * @access protected
+	 *
+	 * @param array $data Array of value arrays. Each value array has the keys
+	 *                    'value' and 'charset'. An optional 'ascii' key can be
+	 *                    set to false to avoid redundant ASCII checks.
+	 * @return array|WP_Error The $data parameter, with invalid characters removed from
+	 *                        each value. This works as a passthrough: any additional keys
+	 *                        such as 'field' are retained in each value array. If we cannot
+	 *                        remove invalid characters, a {@see WP_Error} object is returned.
+	 */
+	protected function strip_invalid_text( $data ) {
+		// Some multibyte character sets that we can check in PHP.
+		$mb_charsets = array(
+			'ascii'   => 'ASCII',
+			'big5'    => 'BIG-5',
+			'eucjpms' => 'eucJP-win',
+			'gb2312'  => 'EUC-CN',
+			'ujis'    => 'EUC-JP',
+			'utf32'   => 'UTF-32',
+		);
+
+		$supported_charsets = array();
+		if ( function_exists( 'mb_list_encodings' ) ) {
+			$supported_charsets = mb_list_encodings();
+		}
+
+		$db_check_string = false;
+
+		foreach ( $data as &$value ) {
+			$charset = $value['charset'];
+
+			// Column isn't a string, or is latin1, which will will happily store anything.
+			if ( false === $charset || 'latin1' === $charset ) {
+				continue;
+			}
+
+			if ( ! is_string( $value['value'] ) ) {
+				continue;
+			}
+
+			// ASCII is always OK.
+			if ( ! isset( $value['ascii'] ) && $this->check_ascii( $value['value'] ) ) {
+				continue;
+			}
+
+			// Convert the text locally.
+			if ( $supported_charsets ) {
+				if ( isset( $mb_charsets[ $charset ] ) && in_array( $mb_charsets[ $charset ], $supported_charsets ) ) {
+					$value['value'] = mb_convert_encoding( $value['value'], $mb_charsets[ $charset ], $mb_charsets[ $charset ] );
+					continue;
+				}
+			}
+
+			// utf8 can be handled by regex, which is a bunch faster than a DB lookup.
+			if ( 'utf8' === $charset || 'utf8mb3' === $charset || 'utf8mb4' === $charset ) {
+				$regex = '/
+					(
+						(?: [\x00-\x7F]                  # single-byte sequences   0xxxxxxx
+						|   [\xC2-\xDF][\x80-\xBF]       # double-byte sequences   110xxxxx 10xxxxxx
+						|   \xE0[\xA0-\xBF][\x80-\xBF]   # triple-byte sequences   1110xxxx 10xxxxxx * 2
+						|   [\xE1-\xEC][\x80-\xBF]{2}
+						|   \xED[\x80-\x9F][\x80-\xBF]
+						|   [\xEE-\xEF][\x80-\xBF]{2}';
+
+				if ( 'utf8mb4' === $charset) {
+					$regex .= '
+						|    \xF0[\x90-\xBF][\x80-\xBF]{2} # four-byte sequences   11110xxx 10xxxxxx * 3
+						|    [\xF1-\xF3][\x80-\xBF]{3}
+						|    \xF4[\x80-\x8F][\x80-\xBF]{2}
+					';
+				}
+
+				$regex .= '){1,50}                          # ...one or more times
+					)
+					| .                                  # anything else
+					/x';
+				$value['value'] = preg_replace( $regex, '$1', $value['value'] );
+				continue;
+			}
+
+			// We couldn't use any local conversions, send it to the DB.
+			$value['db'] = $db_check_string = true;
+		}
+		unset( $value ); // Remove by reference.
+
+		if ( $db_check_string ) {
+			$queries = array();
+			foreach ( $data as $col => $value ) {
+				if ( ! empty( $value['db'] ) ) {
+					if ( ! isset( $queries[ $value['charset'] ] ) ) {
+						$queries[ $value['charset'] ] = array();
+					}
+
+					// Split the CONVERT() calls by charset, so we can make sure the connection is right
+					$queries[ $value['charset'] ][ $col ] = $this->prepare( "CONVERT( %s USING {$value['charset']} )", $value['value'] );
+				}
+			}
+
+			$connection_charset = $this->charset;
+			foreach ( $queries as $charset => $query ) {
+				if ( ! $query ) {
+					continue;
+				}
+
+				// Change the charset to match the string(s) we're converting
+				if ( $charset !== $connection_charset ) {
+					$connection_charset = $charset;
+					$this->set_charset( $this->dbh, $charset );
+				}
+
+				$this->check_current_query = false;
+
+				$row = $this->get_row( "SELECT " . implode( ', ', $query ), ARRAY_N );
+				if ( ! $row ) {
+					$this->set_charset( $this->dbh, $connection_charset );
+					return new WP_Error( 'wpdb_strip_invalid_text_failure' );
+				}
+
+				$cols = array_keys( $query );
+				$col_count = count( $cols );
+				for ( $ii = 0; $ii < $col_count; $ii++ ) {
+					$data[ $cols[ $ii ] ]['value'] = $row[ $ii ];
+				}
+			}
+
+			// Don't forget to change the charset back!
+			if ( $connection_charset !== $this->charset ) {
+				$this->set_charset( $this->dbh );
+			}
+		}
+
+		return $data;
+	}
+
+	/**
+	 * Strips any invalid characters from the query.
+	 *
+	 * @since 4.2.0
+	 * @access protected
+	 *
+	 * @param string $query Query to convert.
+	 * @return string|WP_Error The converted query, or a {@see WP_Error} object if the conversion fails.
+	 */
+	protected function strip_invalid_text_from_query( $query ) {
+		$table = $this->get_table_from_query( $query );
+		if ( $table ) {
+			$charset = $this->get_table_charset( $table );
+			if ( is_wp_error( $charset ) ) {
+				return $charset;
+			}
+
+			// We can't reliably strip text from tables containing binary/blob columns
+			if ( 'binary' === $charset ) {
+				return $query;
+			}
+		} else {
+			$charset = $this->charset;
+		}
+
+		$data = array(
+			'value'   => $query,
+			'charset' => $charset,
+			'ascii'   => false,
+		);
+
+		$data = $this->strip_invalid_text( array( $data ) );
+		if ( is_wp_error( $data ) ) {
+			return $data;
+		}
+
+		return $data[0]['value'];
+	}
+
+	/**
+	 * Strips any invalid characters from the string for a given table and column.
+	 *
+	 * @since 4.2.0
+	 * @access public
+	 *
+	 * @param string $table  Table name.
+	 * @param string $column Column name.
+	 * @param string $value  The text to check.
+	 * @return string|WP_Error The converted string, or a `WP_Error` object if the conversion fails.
+	 */
+	public function strip_invalid_text_for_column( $table, $column, $value ) {
+		if ( ! is_string( $value ) || $this->check_ascii( $value ) ) {
+			return $value;
+		}
+
+		$charset = $this->get_col_charset( $table, $column );
+		if ( ! $charset ) {
+			// Not a string column.
+			return $value;
+		} elseif ( is_wp_error( $charset ) ) {
+			// Bail on real errors.
+			return $charset;
+		}
+
+		$data = array(
+			$column => array(
+				'value'   => $value,
+				'charset' => $charset,
+				'ascii'   => false,
+			)
+		);
+
+		$data = $this->strip_invalid_text( $data );
+		if ( is_wp_error( $data ) ) {
+			return $data;
+		}
+
+		return $data[ $column ]['value'];
+	}
+
+	/**
+	 * Find the first table name referenced in a query.
+	 *
+	 * @since 4.2.0
+	 * @access protected
+	 *
+	 * @param string $query The query to search.
+	 * @return string|false $table The table name found, or false if a table couldn't be found.
+	 */
+	protected function get_table_from_query( $query ) {
+		// Remove characters that can legally trail the table name.
+		$query = rtrim( $query, ';/-#' );
+
+		// Allow (select...) union [...] style queries. Use the first query's table name.
+		$query = ltrim( $query, "\r\n\t (" );
+
+		/*
+		 * Strip everything between parentheses except nested selects and use only 1,000
+		 * chars of the query.
+		 */
+		$query = preg_replace( '/\((?!\s*select)[^(]*?\)/is', '()', substr( $query, 0, 1000 ) );
+
+		// Quickly match most common queries.
+		if ( preg_match( '/^\s*(?:'
+				. 'SELECT.*?\s+FROM'
+				. '|INSERT(?:\s+LOW_PRIORITY|\s+DELAYED|\s+HIGH_PRIORITY)?(?:\s+IGNORE)?(?:\s+INTO)?'
+				. '|REPLACE(?:\s+LOW_PRIORITY|\s+DELAYED)?(?:\s+INTO)?'
+				. '|UPDATE(?:\s+LOW_PRIORITY)?(?:\s+IGNORE)?'
+				. '|DELETE(?:\s+LOW_PRIORITY|\s+QUICK|\s+IGNORE)*(?:\s+FROM)?'
+				. ')\s+`?([\w-]+)`?/is', $query, $maybe ) ) {
+			return $maybe[1];
+		}
+
+		// SHOW TABLE STATUS and SHOW TABLES
+		if ( preg_match( '/^\s*(?:'
+				. 'SHOW\s+TABLE\s+STATUS.+(?:LIKE\s+|WHERE\s+Name\s*=\s*)'
+				. '|SHOW\s+(?:FULL\s+)?TABLES.+(?:LIKE\s+|WHERE\s+Name\s*=\s*)'
+				. ')\W([\w-]+)\W/is', $query, $maybe ) ) {
+			return $maybe[1];
+		}
+
+		// Big pattern for the rest of the table-related queries.
+		if ( preg_match( '/^\s*(?:'
+				. '(?:EXPLAIN\s+(?:EXTENDED\s+)?)?SELECT.*?\s+FROM'
+				. '|DESCRIBE|DESC|EXPLAIN|HANDLER'
+				. '|(?:LOCK|UNLOCK)\s+TABLE(?:S)?'
+				. '|(?:RENAME|OPTIMIZE|BACKUP|RESTORE|CHECK|CHECKSUM|ANALYZE|REPAIR).*\s+TABLE'
+				. '|TRUNCATE(?:\s+TABLE)?'
+				. '|CREATE(?:\s+TEMPORARY)?\s+TABLE(?:\s+IF\s+NOT\s+EXISTS)?'
+				. '|ALTER(?:\s+IGNORE)?\s+TABLE'
+				. '|DROP\s+TABLE(?:\s+IF\s+EXISTS)?'
+				. '|CREATE(?:\s+\w+)?\s+INDEX.*\s+ON'
+				. '|DROP\s+INDEX.*\s+ON'
+				. '|LOAD\s+DATA.*INFILE.*INTO\s+TABLE'
+				. '|(?:GRANT|REVOKE).*ON\s+TABLE'
+				. '|SHOW\s+(?:.*FROM|.*TABLE)'
+				. ')\s+\(*\s*`?([\w-]+)`?\s*\)*/is', $query, $maybe ) ) {
+			return $maybe[1];
+		}
+
+		return false;
+	}
+
+	/**
 	 * Load the column metadata from the last query.
 	 *
 	 * @since 3.5.0
