MySQL學習總結(4)-表級操作語句
1.建立資料表
語句:create table [if not exists] table_name(
column_name data_type,
......
);
2.檢視資料表列表
show tables [from db_name]
[like ‘pattern’ | where expr]
(1)檢視當前資料表(已開啟的)
(2)檢視非當前資料表
3檢視資料表的建立命令
4.檢視資料表結構show columns from table_name;或desc table_name;
5.外來鍵約束操作
foreign key(子表外來鍵列欄位名)references 父表名(參照列)
6.修改資料表語句
alter table table_name 修改操作1(添/刪),修改操作2(添/刪);
(1)新增單列
alter table table_name add [column] col_name col_definition [first | after col_name ];
欄位位置:預設最後、first(最前)、after(col_name後)
(2)新增多列
alter table table_name add [column] (col_name col_definition,...);
(3)刪除列
alter table table_name drop [column] col_name;
7.新增主鍵約束
alter table tbl_name add [constraint[symbol*約束標記*]] primary key[index_type](index_col_name);
8.新增唯一約束
alter table tbl_name add [constraint[symbol]] unique [index | key] [index_name] [index_type] (index_col_name,...);
9.新增外來鍵約束
alter table tbl_name add [constraint[symbol]] foreign key [index_name] (index_col_name,...) reference_definition;
10.新增/刪除預設約束
alter table tbl_name alter[column] col_name {set default literal | drop default};
11.刪除主鍵約束
alter table tbl_name drop primary key;
12.刪除唯一約束
alter table tbl_name drop {index | key} index_name;
13.刪除外來鍵約束
alter table tbl_name drop foreign key fk_symbol;
查看錶的建立命令,找到外來鍵約束標記
14.修改列定義
alter table tbl_name modify[column]col_name col_definition [first | after col_name];
15.修改列名稱
alter table tbl_name change[column]old_col_name new_col_name col_definition [first | after col_name]
change比modify功能多
16.資料表更名
方法1
alter table tbl_name rename [to | as] new_tbl_name
方法2
rename table tbl_name to new_tbl_name [,tbl_name2 to new_tbl_name2]...
17.連線(join)
(1)update tdb_goods inner join tdb_goods_cates on goods_cate=cate_name
set goods_cate=cate_id;
18.建立資料表同時將查詢結果寫入到資料表
create table [if not exists] tbl_name
[(create_definition,...)]
select_statement
19.欄位名不明確處理
update tdb_goods as g inner join tdb_goods_brands as b on g.brand_name=b.brand_name
set g.brand_name=b.brand_id;
20.多表刪除(Join作為篩選條件用於delete)
Delete tbl_name[.*] [,tbl_name[.*]]...
From table_references
[where where_condition]
21.修改儲存引擎的方法
(1)通過修改mysql配置檔案(my.ini)實現
default-storage-engine=engine_name
(2)通過建立資料表命令實現
create table table_name(
...
...
)engine [=] engine_name;
(3)通過修改資料表命令實現
alter table table_name engine [=] engine_name;