mysql 區間/替換/自增/where與having/字段運算/關鍵詞/修改字段

sql的where條件數據量小的時候無所謂，若是數據量大的時候多條件搜索需將排除範圍大的排到前面，數值型排到前面等規則會減小搜索時間。

alter table card_11201 MODIFY house TINYINT(1) DEFAULT 0;
添加用add

設置默認值

ALTER TABLE u_user_9 ALTER COLUMN `power` SET DEFAULT ''

mysql 區間搜索

BETWEEN配合and也能夠配合not盡心val1和val2直接範圍搜索

WHERE column BETWEEN value1 AND value2
WHERE column NOT BETWEEN value1 AND value2

替換字符串內部份內容

UPDATE  `表名`  SET 字段=  REPLACE ( 字段,'原內容','新內容' ) WHERE 條件可選;

數值字段加隨機30~300+350的數

update xxl_article_21 set hits = hits + (RAND()*300+350) WHERE hits<350;

數值類自增

update student set score=score+1 where id = 1

關鍵詞搜索//%任意，_ 匹配單個字符

SELECT * FROM 表名 WHERE 字段名 like "%關鍵詞%" LIMIT 10;

SELECT * FROM 表名 WHERE 字段名 like "%關鍵詞__" LIMIT 10;

將字段1複製到字段2

UPDATE xxl_article_21 m1,xxl_article_21 m2 SET m1.hitsfalse=m2.hits WHERE m1.itemid=m2.itemid

可將字段做爲變量進行運算，where是爲查詢前條件，having是爲查詢分組後條件

SELECT contacts,SUM(addtime-edittime) as time FROM xxl_event2017 where addtime>141111111 GROUP BY contacts HAVING time >86400

from_unixtime 時間戳轉日期時間 

SELECT phone_num,FROM_UNIXTIME(reg_time) as time  from end_user WHERE phone_num = 18500000000
UNIX_TIMESTAMP(‘2018-3-1’);與之相反，日期轉時間戳