SQL statements are
categorized into two categories: DDL statements & DML statements.
DDL is abbreviation for data definition language while DML is
abbreviation for data manipulation language. Data definition language
statement is used to define the data structure of database, in
addition to this; it can modify the structure of the table or other
objects like view, stored procedure and many more. Data manipulation
language statement is used to retrieve data or work with data in SQL
server. Both of these categories contain several statements than I
have present in this article.
Data
Definition Language (DDL):
You can use this statement for create,
drop, truncate, and alter data structure in an instance of SQL server
database. Some of the popular DDL statements are described below.
Create Statement:
This statement is used for creating a new entity; like table, view,
database, index, and many more.
CREATE
TABLE <table name> ( <attribute name 1> <data type 1>,
...<attribute name n> <data type n>);
Alter Statement:
This statement is used for modifying the definition of a an entity;
like table, view, database, index, and many more.
ALTER
TABLE <table name> ADD CONSTRAINT <constraint name>
PRIMARY KEY (<attribute list>);
Drop Statement:
You can use this statement to remove an existing entity; like table,
view, database, index, and many more.
DROP
TABLE <table name>;
Truncate
Statement: This statement removes all
the rows from the table. It is similar to the DELETE statement with
'Where' clause.
TRUNCATE
TABLE <table name>;
Note: In all above
examples; I have taken table as an entity.
Data
Manipulation Language (DML):
Basically this statement is used to work with data in the SQL server
database. Some of the popular DML statements are as follows:
Insert Statement:
As the name suggests; it is used to insert one or more rows in the
table.
INSERT
INTO <table name> VALUES (<value 1>, ... <value n>);
Update statement:
You can use this statement to change the data from in a table.
UPDATE
<table name> SET <attribute> = <expression> WHERE
<condition>;
Delete Statement:
As I have discussed above; it is similar to the truncate statement
but with 'Where' clause. It removes one or more rows from the table.
DELETE
FROM <table name> WHERE <condition>;
