Share examples of MySQ functions

This article introduces some common functions of MySQ functions.

IF(expr,v1,v2) Returns v1 when the expr expression is true, otherwise returns v2

##IFNULL(v1, v2) If v1 is NULL, return v2; if v1 is not NULL, return v1

CASE expr WHEN v1 THEN r1 [WHEN v2 THEN r2][......] [ELSE m ] END

If expr is equal to the value in v1.v2.., return r1, r2.. after THEN. Otherwise, return the value m

## after THEN. #CASE WHEN v1 THEN r1 [WHEN v2 THEN r2][...] [ELSE m] END

When a value in v1, v2... is true, return the value after THEN , otherwise return the value after ELSE

##VERSION() Return the version of MySql

##CONNECTION_ID() Return the current Mysql Number of connections

SHOW PROCESSLIST; SHOW FULL PROCESSLIST; Display running threads

DATEBASE(),SCHEMA( ) Return the current database

##USER(), CURRENT_USER(), SYSTEM_USER(), SESSION_USER() Return the current user name

CHARSET(str) Returns the character set of str

COLLATION(str) Returns the character arrangement of str

LAST_INSERT_ID() Returns the last id value generated by AUTO_INCREMENT. If data is inserted in batches, returns the first one in the batch

Encryption--MD5(str ) Return str MD5 encryption 32-digit hexadecimal

Encryption ENCODE (str, pwd_str) Use pwd_str as the password to encrypt str, a binary string with the same length as str

Decrypt DECODE('str', pwd_str) Use pwd_str as the password to decrypt str, which is the inverse function of the above ENCODE()

FORMAT(x,n) Format the number Convert N from the from_base base to the to_base base

##BENCHMARK(count, expr) Repeat expr for a total of count times

CONVERT(str USING charset) Convert str to the corresponding charset

CAST(x AS type), CONVERT(x, type) Return to convert x to type Value of type

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