Merge & Multiple Inserts
USING MERGE
MERGE
You can use merge command to perform insert and update in a single command.
Ex:
SQL> Merge into student1 s1
Using (select *From student2) s2
On(s1.no=s2.no)
When matched then
Update set marks = s2.marks
When not matched then
Insert (s1.no,s1.name,s1.marks)
Values(s2.no,s2.name,s2.marks);
In the above the two tables are with the same structure but we can merge different structured
tables also but the datatype of the columns should match.
Assume that student1 has columns like no,name,marks and student2 has columns like no,
name, hno, city.
SQL> Merge into student1 s1
Using (select *From student2) s2
On(s1.no=s2.no)
When matched then
Update set marks = s2.hno
When not matched then
Insert (s1.no,s1.name,s1.marks)
Values(s2.no,s2.name,s2.hno);
MULTIBLE INSERTS
We have table called DEPT with the following columns and data
DEPTNO DNAME LOC
-------- -------- ----
10 accounting new york
20 research dallas
30 sales Chicago
40 operations boston
a) CREATE STUDENT TABLE
SQL> Create table student(no number(2),name varchar(2),marks number(3));
b) MULTI INSERT WITH ALL FIELDS
SQL> Insert all
Into student values(1,’a’,100)
Into student values(2,’b’,200)
Into student values(3,’c’,300)
Select *from dept where deptno=10;
-- This inserts 3 rows
c) MULTI INSERT WITH SPECIFIED FIELDS
SQL> insert all
Into student (no,name) values(4,’d’)
Into student(name,marks) values(’e’,400)
Into student values(3,’c’,300)
Select *from dept where deptno=10;
-- This inserts 3 rows
d) MULTI INSERT WITH DUPLICATE ROWS
SQL> insert all
Into student values(1,’a’,100)
Into student values(2,’b’,200)
Into student values(3,’c’,300)
Select *from dept where deptno > 10;
-- This inserts 9 rows because in the select statement retrieves 3 records (3 inserts for each
row retrieved)
e) MULTI INSERT WITH CONDITIONS BASED
SQL> Insert all
When deptno > 10 then
Into student1 values(1,’a’,100)
When dname = ‘SALES’ then
Into student2 values(2,’b’,200)
When loc = ‘NEW YORK’ then
Into student3 values(3,’c’,300)
Select *from dept where deptno>10;
-- This inserts 4 rows because the first condition satisfied 3 times, second condition
satisfied once and the last none.
f) MULTI INSERT WITH CONDITIONS BASED AND ELSE
SQL> Insert all
When deptno > 100 then
Into student1 values(1,’a’,100)
When dname = ‘S’ then
Into student2 values(2,’b’,200)
When loc = ‘NEW YORK’ then
Into student3 values(3,’c’,300)
Else
Into student values(4,’d’,400)
Select *from dept where deptno>10;
-- This inserts 3 records because the else satisfied 3 times
g) MULTI INSERT WITH CONDITIONS BASED AND FIRST
SQL> Insert first
When deptno = 20 then
Into student1 values(1,’a’,100)
When dname = ‘RESEARCH’ then
Into student2 values(2,’b’,200)
When loc = ‘NEW YORK’ then
Into student3 values(3,’c’,300)
Select *from dept where deptno=20;
-- This inserts 1 record because the first clause avoid to check the remaining conditions
once the condition is satisfied.
h) MULTI INSERT WITH CONDITIONS BASED, FIRST AND ELSE
SQL> Insert first
When deptno = 30 then
Into student1 values(1,’a’,100)
When dname = ‘R’ then
Into student2 values(2,’b’,200)
When loc = ‘NEW YORK’ then
Into student3 values(3,’c’,300)
Else
Into student values(4,’d’,400)
Select *from dept where deptno=20;
-- This inserts 1 record because the else clause satisfied once
i) MULTI INSERT WITH MULTIBLE TABLES
SQL> Insert all
Into student1 values(1,’a’,100)
Into student2 values(2,’b’,200)
Into student3 values(3,’c’,300)
Select *from dept where deptno=10;
-- This inserts 3 rows
** You can use multi tables with specified fields, with duplicate rows, with conditions, with
first and else clauses.