mysql sql 使用记录

1. 修改字符集：

查看数据库字符集
show VARIABLES like 'character%';

ALTER TABLE  yljg DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
    
修改数据库字符集
ALTER TABLE  dept DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
    
    
查看    列字符集
SHOW FULL COLUMNS FROM dept;
    
SHOW FULL COLUMNS FROM yljg;
    
修改列字符集
ALTER TABLE yljg CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;

2. left join  跨表update, 表内互相update

SELECT * FROM yljg t left join dept B on t.JGZDYBM = B.DEPTCODE
WHERE B.parentcode != 0 AND t.xzqhdm IN ('370724' , ' 370725', '370789')
    
SELECT * from dept WHERE parentcode != '0'
    
    
UPDATE yljg t, dept B SET t.SJJGBM = B.PARENTCODE 
    
WHERE t.JGZDYBM = B.DEPTCODE AND  xzqhdm IN ('370724' , ' 370725', '370789')
        
SELECT * FROM yljg WHERE xzqhdm IN ('370724' , ' 370725', '370789') AND SJJGBM != '0'
    
    
UPDATE yljg t SET sjjgid = (SELECT JGMC FROM yljg m WHERE t.SJJGBM = m.JGZDYBM) WHERE  t.SJJGBM != '0' AND t.xzqhdm IN ('370724' , ' 370725', '370789')
UPDATE yljg t SET xzjddm = (SELECT xzjddm FROM yljg m WHERE t.SJJGBM = m.JGZDYBM) WHERE  t.SJJGBM != '0' AND t.xzqhdm IN ('370724' , ' 370725', '370789')
UPDATE yljg t SET xzjdmc = (SELECT xzjdmc FROM yljg m WHERE t.SJJGBM = m.JGZDYBM) WHERE  t.SJJGBM != '0' AND t.xzqhdm IN ('370724' , ' 370725', '370789')