MySQL字符串转换数字

mysql将字符串转为数字的方法：

• 1、利用“+”运算符，语法“'字符串' + 0”；

SELECT JSON_EXTRACT(charge_sts,'$.waiter') k1,JSON_EXTRACT(charge_sts,'$.waiter')+0 k2,'0121' k3,'012'+0 k4 from test

• 2、利用cast()函数，语法“cast('字符串' as 数值类型)”；

SELECT JSON_EXTRACT(charge_sts,'$.waiter') k1,CAST(JSON_EXTRACT(charge_sts,'$.waiter') AS SIGNED) k2,'0121' k3,CAST('012' AS SIGNED) k4 from mo_loan_order_charge HAVING k2=0;

• 3、利用convert()函数，语法“convert('字符串', 数值类型)”。

SELECT JSON_EXTRACT(charge_sts,'$.waiter') k1,CONVERT(JSON_EXTRACT(charge_sts,'$.waiter'),SIGNED) k2,'0121' k3,CONVERT('012',SIGNED) k4 from mo_loan_order_charge HAVING k2=0;

备注：数值类型(三种)：

• 整数: SIGNED
• 无符号整数: UNSIGNED
• 浮点数: DECIMAL