Question

CREATE TEMP TABLE var(name VARCHAR(255),integer INT(5),string VARCHAR(255)); -- my variables

CREATE TEMP TABLE param(name VARCHAR(255),integer INT(5),string VARCHAR(255)); -- my parameters

INSERT INTO param (name,string) VALUES('search',''); -- assigning my parameters
INSERT INTO param (name,string) VALUES('page',1);
INSERT INTO param (name,integer) VALUES('rows',10);

INSERT INTO var (name,integer) VALUES('initindex',( (SELECT integer FROM param WHERE name='page') - 1 ) * (SELECT integer FROM param WHERE name='rows')); --calculating my variable using the parameters

SELECT CASE (SELECT string FROM param WHERE name='search') -- querying
WHEN '' THEN (SELECT * FROM clients ORDER BY id ASC LIMIT 10 OFFSET (SELECT integer FROM var WHERE name='initindex'))
ELSE
    (SELECT * FROM clients
    WHERE id LIKE '%'||(SELECT string FROM param WHERE name='search')||'%'
    OR name LIKE '%'||(SELECT string FROM param WHERE name='search')||'%'
    OR first_date= (SELECT string FROM param WHERE name='search')
    OR last_date= (SELECT string FROM param WHERE name='search')
    OR pass LIKE '%'||(SELECT string FROM param WHERE name='search')||'%'
    ORDER BY id ASC LIMIT (SELECT integer FROM param WHERE name='rows') OFFSET (SELECT integer FROM var WHERE name ='initindex'))
END
FROM clients;
DROP TABLE var;
DROP TABLE param;

当我执行整个查询时，我收到一个错误：

[19:07:08]在数据库'DataBase'上执行SQL查询时出错：只有一个结果允许作为表达式一部分的SELECT

此外，当我执行每个子查询时，它只会产生一个唯一的行。因为表var和param（模拟为MySQL语法中的变量和参数）总是只返回一个值。

SELECT CASE - 那么 - 当查询抛出错误时

0 个答案: