Question

我想选择列id_thread，no_tlp和nama（联系人姓名）

但并非所有号码都保存在tb_contact上（例如：来自sms-gateway的sms地址，它们具有自动名称值）

所以如果nama = NULL则设置＆＃39; nama＆＃39; =＆＃39; no_tlp＆＃39;

SELECT 
    id_thread, no_tlp, 
    IF(tb_contact.`nama` = 'NULL' THEN SET nama = no_tlp) AS nama  
FROM
    tb_sms
LEFT JOIN 
    tb_contact ON  tb_sms.`no_tlp` = tb_contact.`no_tlp` 
GROUP BY 
    id_thread ASC

这是我的查询，但它没有用，

请有人帮助我

Answer 1

试试这个;）

SELECT id_thread, tb_contact.`no_tlp`, IF(tb_contact.`nama` IS NULL, tb_contact.`no_tlp`, tb_contact.`nama`) AS nama  
FROM tb_sms
LEFT JOIN tb_contact 
ON  tb_sms.`no_tlp` = tb_contact.`no_tlp` 
GROUP BY id_thread ASC

或使用COALESCE之类的：

SELECT id_thread, tb_contact.`no_tlp`, COALESCE(tb_contact.`nama`, tb_contact.`no_tlp`) AS nama  
FROM tb_sms
LEFT JOIN tb_contact 
ON  tb_sms.`no_tlp` = tb_contact.`no_tlp` 
GROUP BY id_thread ASC

Answer 2

请尝试此sql查询。

SELECT id_thread, no_tlp, CASE  WHEN tb_contact.`nama` = 'NULL'  THEN no_tlp END AS nama  
FROM tb_sms
LEFT JOIN tb_contact 
ON  tb_sms.`no_tlp` = tb_contact.`no_tlp` 
GROUP BY id_thread ASC

如何在mysql中使用IF子句进行SELECT查询

2 个答案: