SELECT STATEMENT:
SELECTING ALL COLUMNS OF THE TABLE:
A ‘SELECT’ statement is used as a DATA RETRIEVAL statement i.e. It retrieves information from the database.
SYNTAX:
SQL> SELECT * FROM TABLE NAME;
• SELECT identifies WHAT COLUMNS.
• FROM identifies WHICH TABLE.
Simply, SELECT clause specify which column is to be displayed & FROM clause specify the table containing the columns listed in the SELECT clause.
Here, ‘*’ is used to select all columns.
SELECTING SPECIFIC COLUMNS OF THE TABLE:
SYNTAX:
SQL> SELECT ENAME,JOB FROM EMP
SELECTING DISTINCT ELEMENTS FROM THE TABLE:
SYNTAX:
SQL> SELECT DISTINCT ENAME,JOB FROM EMP
The SELECT DISTINCT statement is used to return only distinct (different) values.It is used to remove duplicate values.
SQL> select * from empxyz;
NAME AGE ----------------------- ------ anju 23 jkg 34 anju 23
SQL> select distinct name,age from empxyz;
NAME AGE ----------------------- ------- anju 23 jkg 34
INSERT STATEMENT:
SYNTAX:
SQL> INSERT into CSE(student,rollno) VALUES ('MONIKA',651);
INSERT statement is used to ADD NEW ROW TO A TABLE.
Using INSERT We can only insert on row at a time. As shown in above example,
In above example CSE is the name of the TABLE & STUDENT, ROLLNO are its two ATTRIBUTES.
Enclose CHARACTER & DATE values within a SINGLE QUOTATION MARKS.
DELETE STATEMENT:
SYNTAX:
SQL> DELETE from CSE where rollno BETWEEN 605 AND 630;
i.e. DELETE FROM table [WHERE condition];
If we OMIT WHERE CLAUSE then ALL ROWS OF THE COLUMN ARE DELETED.
UPDATE STATEMENT:
SYNTAX:
SQL> UPDATE cse SET rollno=21 WHERE student='ITIKA';
Here, If we do not use WHERE clause then ALL ROWS OF THE TABLE ARE UPDATED.
SPCIFIED ROW or ROWS are modified if we specify the WHERE clause
