day1:
表格字段查詢
select * from tablename #全字段查詢
select id from tablename #字段"id"查詢 (單字段查詢)
select id,name from tablename #多字段查詢(字段名用逗號分隔)
條件查詢
select * from tablename where age<30 # where 表示條件關鍵字
select * from tablename where name='ken' # 條件值加單引號
邏輯運算符:
< = > <= >= 不等: != <>
day2
多條件查詢
SELECT * FROM yinxiong WHERE v_age>30 AND v_age <50 #且
SELECT * FROM yinxiong WHERE v_age>30 or v_age <20 # 或
區間查詢
SELECT * FROM yinxiong WHERE v_age BETWEEN 10 and 50 # 區間爲 and 前後 (10到50)
SELECT * FROM yinxiong WHERE v_age in (10 ,50) # 特定值集合查詢 (10或50)
排序
SELECT * FROM yinxiong ORDER BY v_age # order by 默認正序( 升序)
SELECT * FROM yinxiong ORDER BY v_age DESC # 正需(ASC) 倒序(desc)
模糊查詢
SELECT * FROM yinxiong WHERE v_name like '%喬%' #特定關鍵字模糊查詢
v_name中含有“喬”字的記錄、
若 ’喬%‘ 只能在首位
若 ’%喬‘ 只能在末位
分頁查詢
SELECT * FROM yinxiong LIMIT 0,4 #從0開始 往後4條數據(1,2,3,4)
SELECT * FROM yinxiong LIMIT 4 #當前分頁四條數據