A few useful functions in MySQL

1. From_unixtime
effect: Displays the time in MySQL as an int (11) in the "YYYY-MM-DD" format. Example:

Select Mtime, From_unixtime (mtime) from topics limit 10;

2. CONCAT (str1,str2,...) Function: Will str1, str2 ... Connect as a string. If any one of the arguments is NULL, the return value is null. Cases:

Update video Set playlink = Concat (Playlink, ' &FR=ABCD ');

All the tables in theAdd a fr parameter to the Playlink
3. CONVERT(value, type); function: Converts a value of one type to another type

There is a limit to the types that can be converted. This type can be one of the following values:

-binary, with binary prefix effect: binary-character type, parameter: CHAR ()-Date: Date-time: Time-datetime type: DATETIME -Floating point: Decimal-integer: Signed-unsigned integer: UNSIGNED example: Suppose there is a money field, in order not to lose the precision of its decimals, we use varchar to record its value. But then there is a problem, what if you want to compare the size of this field with the number?

SELECT * from Bill where to convert (money, DECIMAL) > 100;

Several useful functions in MySQL