In MySQL, BENCHMARK() is a built-in function that executes an expression repeatedly for a specified number of times.
It can be used to time how quickly MySQL processes the expression. Specifically, the function is intended for measuring the runtime performance of scalar expressions.
The result is always 0, or NULL for inappropriate arguments. The function is intended to be used within the mysql command line tool, which reports query execution times.
By default, time zone names aren’t included with MySQL. The MySQL installation process creates the appropriate tables, but it doesn’t populate these tables.
That said, it’s very easy to populate these tables.
Once populated, we can list out the time zone names available in our system by querying the mysql.time_zone_name table.
In MySQL, COLLATION() is a built in function that returns the collation of its string argument.
We provide the string when we call the function.
In MySQL, CHARSET() is a built in function that returns the character set of its string argument.
We provide the string when we call the function.
If you’re getting an error in MySQL that reads something like “ERROR 1054 (42S22): Unknown column ‘c.DogName’ in ‘on clause”“, here are three likely causes:
In MySQL, CONVERT() is a built in function that converts a value to another data type. It takes a value of one type and returns a value of the specified type.
We provide the value as an argument when we call the function, as well as the type that we want it converted to.
The CONVERT() function is similar to the CAST() function, which also converts between data types.
In MySQL, ROW_COUNT() is a built-in function that returns the number of rows updated, inserted, or deleted by the preceding statement.
The value returned by ROW_COUNT() is often the same as the row count that the mysql client displays following statement execution, as well as the value from the mysql_affected_rows() C API function.
In MySQL, FORMAT_BYTES() is a built in function that converts a numeric byte count to a more human-readable format. It returns a string consisting of the value and a units indicator.
We provide the numeric byte count when we call the function.
If you’re getting error number 1064 that reads something like “1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘INTEGER )’ at line 1“, it could be that you’re using the wrong term for the integer.
MySQL doesn’t let us use just the INTEGER keyword when converting to an integer. We need to use either SIGNED or UNSIGNED, optionally followed by INTEGER or INT. When we do this, it produces a signed or unsigned BIGINT value.