Oracle,sqlserver,mysql Database Statement Tables

--Creating a table statement
ORACLE:
CREATE TABLE _table_name (
Column1 varchar2 () primary key,
Column2 number (5) not nul L,
Memo varchar2
),
Comment on column _table_name.column1
is ' This is column1 comment ';
SQL Server:
CREATE TABLE _table_name (
Column1 varchar () primary key,
Column2 int not NULL,
Memo varchar ( )
);
MYSQL:
Create table ' _table_name '
(
' Column1 ' VARCHAR () primary key COMMENT ' annotations ',
' Column2 ' varcha R () NOT null COMMENT ' annotations ',
PRIMARY key (' Column1 ')--the primary key definition can also be placed here
Engine=innodb DEFAULT CHARSET=GBK;

--Modify a field statement
ORACLE:
ALTER TABLE _table_name add/modify column_name varchar2 (505);
ALTER TABLE _table_name DR OP column column_name;
SQL Server:
ALTER TABLE _table_name add column_name VARCHAR;
ALTER TABLE _table_name ALTER COLUMN Column_ Name varchar (2000);
ALTER TABLE _table_name drop column column_name;
MYSQL:
ALTER TABLE _table_name add/modify column column_name varchar (watts);
ALTER TABLE _table_name drop ' Co Lumn_name ';

--Create DELETE index statement, index can only delete rebuild, cannot modify
ORACLE:
--PRIMARY key index
ALTER TABLE _TABLE_NAME add constraint index_name primary key (c olumn_name) using index tablespace URMSPK;
--Normal column index
CREATE index Index_name$cl2 on _table_name (column1_name,column2_name DESC) tablespace urmsidx;
--delete In addition to the Index
Drop index index_name;
SQL Server:
--primary key index
Alter table _table_name Add primary key (COLUMN_NAME);
ALTER TABLE _table_name add Constrai NT Index_name primary key CLUSTERED (column_name)
with (
Pad_index = off,
Ignore_dup_key = off,
STATISTICS _norecompute = off,
Allow_row_locks = on,
Allow_page_locks = on)
on URMSPK
Go

--Normal column index, non-unique index needs to be removed Unique nonclustered keyword
CREATE unique nonclustered INDEX [index_name] on [_table_name]
([Orgrange], [Showorder] D ESC)
with (
Pad_index = off,
Ignore_dup_key = off,
Drop_existing = off,
Statistics_norecompute = off,< br> sort_in_tempdb = off,
ONLINE = off,
Allow_row_locks = ON,
Allow_page_locks = ON)
on [urmsidx]
Go
--delete index
Drop index _table_name.idxname;
MYSQL:
--normal index
ALTER TABLE _table_name ADD index index_name (APPID, CreateDate DESC);
-Unique index
ALTER TABLE _table_name ADD UNIQUE index_name (column_list);
--PRIMARY key index
ALTER TABLE _table_name ADD PRIMARY key index_name (column_list);
 

--Delete Index
ALTER TABLE _table_name DROP INDEX index_name;

--INSERT statement
ORACLE:
Insert into _table_name (column_list) VALUES (' value_list ');
Sql server:
Insert into _table_name (column_list) VALUES (' value_list ');
Mysql:
Insert into Umframeset (' column_list ') VALUES (' Value_list '), (' Value_list2 ');--You can insert more than one record

--Modifying the table name
ORACLE:
ALTER TABLE leave Rename to Leave01;
Sql server:
EXEC sp_rename leave,leave01;
Mysql:
ALTER TABLE ' leave ' RENAME to ' leave01 ';
--Delete a table statement
ORACLE:
DROP TABLE table_name;
Sql server:
DROP TABLE table_name;
Mysql:
DROP TABLE table_name
--Delete statements for all tables
Sql server:
EXEC sp_msforeachtable ' drop table? ';
--Modifying column names
Sql server:
EXEC sp_rename ' table name. Column name ', ' new column name ', ' column ';
--Deleting records
ORACLE:
Delete (from) tablename where _column_name=?;