ios - INNER JOIN 查询不起作用

Question

我在两个名为 EMPLOYEE 和 DEPARTMENT 的表上使用 INNERJOIN 查询。存在一个常见的 empID(1234)，它在两个表中都很常见，我想使用连接查询从两个表中获取数据。但它不工作。下面是我的代码:

NSString *querySQL = [NSString stringWithFormat:
@"Select EMPLOYEE.* from EMPLOYEE   INNER JOIN  DEPARTMENT ON  EMPLOYEE.empID = DEPARTMENT.empID =%@",_txtfind.text];

        NSLog(@"fetch query is%@",querySQL);

        const char *query_stmt = [querySQL UTF8String];

        if (sqlite3_prepare_v2(database,
        query_stmt, -1, &statement, NULL) == SQLITE_OK)
        {
             if(sqlite3_step(statement) == SQLITE_ROW)
            {
                NSString *name = [[NSString alloc] initWithUTF8String:
               (const char *) sqlite3_column_text(statement, 0)];
                [resultArray addObject:name];
                NSString *department = [[NSString alloc]   initWithUTF8String:(const char *) sqlite3_column_text(statement, 1)];
                [resultArray addObject:department];
                NSString *year = [[NSString alloc]initWithUTF8String:
                (const char *) sqlite3_column_text(statement, 2)];
                [resultArray addObject:year];
                NSLog(@"result array is %@",resultArray);


            }
           else{
               NSLog(@"Not found");
                    }
            sqlite3_reset(statement);
        }

它总是转到其他部分并显示“未找到”。难道我做错了什么？我的连接查询是否正确？我是 concept 的新手，所以请帮助我，我们非常欢迎您的想法。

Answer 1

这是你的查询，直到 on 子句结束我才理解:

Select EMPLOYEE.*
from EMPLOYEE INNER JOIN 
     DEPARTMENT
     ON EMPLOYEE.empID = DEPARTMENT.empID =%@",_txtfind.text];

也许您需要某种 where 子句？

Select e.*, d.col1, d.col2, . . .
from EMPLOYEE e INNER JOIN 
     DEPARTMENT d
     ON e.empID = d.empID
where e.empId = 'txtfind.text';  -- something like this

无论如何，如果这没有帮助，请编辑您的问题并在变量替换后显示 SQL 查询。