mysql 判断字符串是否数字

MySQL判断字符串是不是数字字符串

2012/8/31 10:10:30table

查询表table_name中col_name（字符串类型）的值是数字的记录 
SELECT col_name,CAST(col_name AS UNSIGNED INTEGER) AS val 
FROM table_name 
WHERE col_name="0" OR col_name>0 
HAVING CHAR_LENGTH(col_name)=CHAR_LENGTH(val);查询