Mysql keeps the existing content and adds content later

This command modifies the data table ff_vod and adds 999999999 after the content of the vod_url field.

update ff_vod set vod_url=CONCAT(vod_url,'999999999') where vod_id BETWEEN 1 AND 42553

The following statement is used to modify only the content with vod_id 1-42553.

where vod_id BETWEEN 1 AND 42553

123WORDPRESS.COM editor analysis:

In fact, this mainly uses the CONCAT function. The MySQL CONCAT() function is used to concatenate multiple strings into one string.

The following will show you how to use the MySQL CONCAT() function.

The MySQL CONCAT() function is used to concatenate multiple strings into one string. It is one of the most important MySQL functions. The following will introduce the MySQL CONCAT() function in detail for your reference.

mysql CONCAT(str1,str2,…)
The return value is a string resulting from the concatenation of the parameters. If any parameter is NULL, the return value is NULL. There may be one or more parameters. If all arguments are nonbinary strings, the result is a nonbinary string. If the argument contains any binary string, the result is a binary string. A numeric argument is converted to its equivalent binary string format; to avoid this, use an explicit type cast, for example: SELECT CONCAT(CAST(int_col AS CHAR), char_col)

mysql> SELECT CONCAT('My', 'S', 'QL');
-> 'MySQL'
mysql> SELECT CONCAT('My', NULL, 'QL');
-> NULL
mysql> SELECT CONCAT(14.3);
-> '14.3'

mysql CONCAT_WS(separator,str1,str2,...)
CONCAT_WS() stands for CONCAT With Separator and is a special form of CONCAT(). The first parameter is the separator for the other parameters. The delimiter is placed between the two strings to be concatenated. The separator can be a string or other parameters. If delimiter is NULL, the result is NULL. The function ignores any NULL values ​​following the separator parameter.

mysql> SELECT CONCAT_WS(',','First name','Second name','Last Name');
-> 'First name, Second name, Last Name'
mysql> SELECT CONCAT_WS(',','First name',NULL,'Last Name');
-> 'First name,Last Name'

mysql CONCAT_WS() does not ignore any empty strings. (However, any NULL values ​​are ignored).