SQL Data Manipulation Language (DML) statements are used to manage data in the tables of a database. DML statements are used for retrieving data from a database, entering new rows to a table in database, making changes to the existing row, removing certain rows from the table etc.
SELECT Statement
SELECT statement is used to retrieve rows from a table
Syntax:
SELECT * from table_name;
SELECT col_1, col_2 from table_name;
Example:
SELECT * FROM HEALTH_DEPT;
SELECT FIRST_NAME, LAST_NAME, AGE, ADDRESS FROM HEALTH_DEPT;
INSERT Statement
INSERT statement is used to insert rows in to a table.
Syntax:
INSERT INTO table_name (col_1, col_2, … col_n) VALUES (value_1, value_2, …value_n);
INSERT INTO table_name VALUES (value_1, value_2, …value_n);
Example:
INSERT INTO HEALTH_DEPT (EMPLOYEE_ID, FIRST_NAME, LAST_NAME, SALARY) VALUES (43, Roka, Simons, 4000);
Or
INSERT INTO HEALTH_DEPT VALUES (43, Roka, Simons, 4000);
UPDATE Statement
UPDATE Statement is used to update selected rows or all rows in a table
Syntax:
UPDATE table_name SET col1=value1, col2=value2, … col_n=value_n WHERE (condition);
Example:
UPDATE HEALTH_DEPT SET SALARY=10000 WHERE ADDRESS=’Mumbai’;
DELETE Statement
This statement is used to delete rows from a table.
Syntax:
DELETE FROM table_name WHERE (condition);
Example:
DELETE FROM HEALTH_DEPT WHERE (SALARY =1000);
TRUNCATE Statement
This statement is used delete all rows from a table
Syntax:
TRUNCATE TABLE table_name
Example:
TRUNCATE TABLE HEALTH_DEPT;