Built-In Function and Operator Reference 2113 Name Description Introduced Deprecated ST_Touches() Whether one geometry touches another ST_Transform() Transform coordinates of geometry 8.0.13 ST_Union() Return point set union of two geometries ST_Validate() Return validated geometry ST_Within() Whether one geometry is within another ST_X() Return X coordinate of Point ST_Y() Return Y coordinate of Point STATEMENT_DIGEST() Compute statement digest hash value STATEMENT_DIGEST_TEXT() Compute normalized statement digest STD() Return the population standard deviation STDDEV() Return the population standard deviation STDDEV_POP() Return the population standard deviation STDDEV_SAMP() Return the sample standard deviation STR_TO_DATE() Convert a string to a date STRCMP() Compare two strings SUBDATE() Synonym for DATE_SUB() when invoked with three arguments SUBSTR() Return the substring as specified SUBSTRING() Return the substring as specified SUBSTRING_INDEX() Return a substring from a string before the specified number of occurrences of the delimiter SUBTIME() Subtract times SUM() Return the sum