sql server learn day2

T-SQL component

 

DML (Data Manipulation Language)

---- query, insert, delete and modify data in the database;

————select、insert、update、delete 等；

The DCL (Data Control Language)

---- is used to control access permissions, access and so on;

————grant、revoke、deny 等；

DDL (Data Definition Language)

---- used to create a database, which database objects and define columns and the like;

————create table、drop table、alter 等；

Variable declaration, flow control, performance function

---- defined variables, branch judgment, cyclic structure;

---- date functions, mathematical functions, string functions, system functions and so on;

 

T-SQL logical operators

Operators	meaning
=	equal
>	more than the
<	Less than
>=	greater than or equal to
<=	less than or equal to
<>	not equal to
!	non-

 

Wildcards

Wildcards	Explanation	Examples
_	A character	a like 'c_'
%	Arbitrary length string	b like 'co_%'
[]	A character in the range specified in brackets	c like '9w01[1-2]
[^]	A character not in the range specified in brackets	d like '%[a-d][^1-2]'