MySQL 程序无法按预期执行

Question

CREATE PROCEDURE `userCredentialsWeight`(IN data1 varchar(50), IN data2 varchar(250))
BEGIN

    /* all declaration */

    IF (SELECT field1 FROM user_credentials WHERE field1 = data1 LIMIT 1 )
    THEN
        SET DATA_WEIGHT = 75;
    ELSE
        SET DATA_WEIGHT = 100;
    END IF;

    /* More calculations here */  ---> this block contains all the calculation,
 actually i am new to procedure, i have done this using 
direct query from application but it requires 4 database requests 
which I want to minimize here

END

现在我的问题是 WHERE 没有获得 data1 的值之后的条件。

平台 - Mysql（我正在使用 MYSQL Workbench）

Answer 1

测试

SELECT CASE WHEN COUNT(*) = 0 
            THEN 100
            ELSE 75
            END
INTO data_weight 
FROM user_credentials
WHERE field1 = data1;