SQL Server/T-SQL/Select Query/EXISTS
Содержание
Checks for existing Product record
<source lang="sql">
12> 13> create table employee( 14> ID int, 15> name nvarchar (10), 16> salary int, 17> start_date datetime, 18> city nvarchar (10), 19> region char (1)) 20> GO 1> 2> insert into employee (ID, name, salary, start_date, city, region) 3> values (1, "Jason", 40420, "02/01/94", "New York", "W") 4> GO 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (2, "Robert",14420, "01/02/95", "Vancouver","N") 3> GO 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (3, "Celia", 24020, "12/03/96", "Toronto", "W") 3> GO 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (4, "Linda", 40620, "11/04/97", "New York", "N") 3> GO 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (5, "David", 80026, "10/05/98", "Vancouver","W") 3> GO 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (6, "James", 70060, "09/06/99", "Toronto", "N") 3> GO 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (7, "Alison",90620, "08/07/00", "New York", "W") 3> GO 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (8, "Chris", 26020, "07/08/01", "Vancouver","N") 3> GO 1> insert into employee (ID, name, salary, start_date, city, region) 2> values (9, "Mary", 60020, "06/09/02", "Toronto", "W") 3> GO 1> 2> select * from employee 3> GO ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
1 Jason 40420 1994-02-01 00:00:00.000 New York W
2 Robert 14420 1995-01-02 00:00:00.000 Vancouver N
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
4 Linda 40620 1997-11-04 00:00:00.000 New York N
5 David 80026 1998-10-05 00:00:00.000 Vancouver W
6 James 70060 1999-09-06 00:00:00.000 Toronto N
7 Alison 90620 2000-08-07 00:00:00.000 New York W
8 Chris 26020 2001-07-08 00:00:00.000 Vancouver N
9 Mary 60020 2002-06-09 00:00:00.000 Toronto W
1> 2> -- Creating a Stored Procedure 3> 4> 5> /* Checks for existing Product record 6~ If exists, updates the record. If not, 7~ inserts new record 8~ */ 9> CREATE PROCEDURE spInsertOrUpdateEmployee 10> -- Input parameters -- 11> @Name nVarChar(50), 12> @City nVarChar(25), 13> @Salary Money 14> AS 15> IF EXISTS(SELECT * From Employee Where Name = @Name) 16> UPDATE Employee SET City = @City, Salary = @Salary 17> WHERE Name = @Name 18> ELSE 19> INSERT INTO Employee (Name, City, Salary) 20> SELECT @Name, @City, @Salary 21> GO 1> 2> EXEC spInsertOrUpdateEmployee @Name="a",@City="b",@Salary=999 3> GO 1> EXEC spInsertOrUpdateEmployee @Name="Mary",@City="b",@Salary=999 2> GO 1> 2> select * FROM employee 3> GO ID name salary start_date city region
---------- ----------- ----------------------- ---------- ------
1 Jason 40420 1994-02-01 00:00:00.000 New York W
2 Robert 14420 1995-01-02 00:00:00.000 Vancouver N
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
4 Linda 40620 1997-11-04 00:00:00.000 New York N
5 David 80026 1998-10-05 00:00:00.000 Vancouver W
6 James 70060 1999-09-06 00:00:00.000 Toronto N
7 Alison 90620 2000-08-07 00:00:00.000 New York W
8 Chris 26020 2001-07-08 00:00:00.000 Vancouver N
9 Mary 999 2002-06-09 00:00:00.000 b W
NULL a 999 NULL b NULL
1> 2> drop procedure spInsertOrUpdateEmployee 3> drop table employee 4> GO 1> 2>
</source>
EXISTS function can be used to represent the ANY and ALL operators
<source lang="sql">
35> 36> 37> 38> CREATE TABLE employee (emp_no INTEGER NOT NULL, 39> emp_fname CHAR(20) NOT NULL, 40> emp_lname CHAR(20) NOT NULL, 41> dept_no CHAR(4) NULL) 42> 43> insert into employee values(1, "Matthew", "Smith", "d3") 44> insert into employee values(2, "Ann", "Jones", "d3") 45> insert into employee values(3, "John", "Barrimore","d1") 46> insert into employee values(4, "James", "James", "d2") 47> insert into employee values(5, "Elsa", "Bertoni", "d2") 48> insert into employee values(6, "Elke", "Hansel", "d2") 49> insert into employee values(7, "Sybill", "Moser", "d1") 50> 51> select * from employee 52> GO (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) emp_no emp_fname emp_lname dept_no
-------------------- -------------------- -------
1 Matthew Smith d3
2 Ann Jones d3
3 John Barrimore d1
4 James James d2
5 Elsa Bertoni d2
6 Elke Hansel d2
7 Sybill Moser d1
(7 rows affected) 1> 2> 3> CREATE TABLE department(dept_no CHAR(4) NOT NULL, 4> dept_name CHAR(25) NOT NULL, 5> location CHAR(30) NULL) 6> 7> insert into department values ("d1", "developer", "Dallas") 8> insert into department values ("d2", "tester", "Seattle") 9> insert into department values ("d3", "marketing", "Dallas") 10> 11> select * from department 12> GO (1 rows affected) (1 rows affected) (1 rows affected) dept_no dept_name location
------------------------- ------------------------------
d1 developer Dallas d2 tester Seattle d3 marketing Dallas (3 rows affected) 1> 2> CREATE TABLE works_on (emp_no INTEGER NOT NULL, 3> project_no CHAR(4) NOT NULL, 4> job CHAR (15) NULL, 5> enter_date DATETIME NULL) 6> 7> insert into works_on values (1, "p1", "analyst", "1997.10.1") 8> insert into works_on values (1, "p3", "manager", "1999.1.1") 9> insert into works_on values (2, "p2", "clerk", "1998.2.15") 10> insert into works_on values (2, "p2", NULL, "1998.6.1") 11> insert into works_on values (3, "p2", NULL, "1997.12.15") 12> insert into works_on values (4, "p3", "analyst", "1998.10.15") 13> insert into works_on values (5, "p1", "manager", "1998.4.15") 14> insert into works_on values (6, "p1", NULL, "1998.8.1") 15> insert into works_on values (7, "p2", "clerk", "1999.2.1") 16> insert into works_on values (8, "p3", "clerk", "1997.11.15") 17> insert into works_on values (7, "p1", "clerk", "1998.1.4") 18> 19> select * from works_on 20> GO (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) emp_no project_no job enter_date
---------- --------------- -----------------------
1 p1 analyst 1997-10-01 00:00:00.000
1 p3 manager 1999-01-01 00:00:00.000
2 p2 clerk 1998-02-15 00:00:00.000
2 p2 NULL 1998-06-01 00:00:00.000
3 p2 NULL 1997-12-15 00:00:00.000
4 p3 analyst 1998-10-15 00:00:00.000
5 p1 manager 1998-04-15 00:00:00.000
6 p1 NULL 1998-08-01 00:00:00.000
7 p2 clerk 1999-02-01 00:00:00.000
8 p3 clerk 1997-11-15 00:00:00.000
7 p1 clerk 1998-01-04 00:00:00.000
(11 rows affected) 1> -- EXISTS function can be used to represent the ANY and ALL operators 2> 3> SELECT emp_fname, emp_lname FROM employee WHERE EXISTS 4> (SELECT * FROM works_on WHERE project_no = "p1" 5> AND employee.emp_no = works_on.emp_no) 6> GO emp_fname emp_lname
--------------------
Matthew Smith Elsa Bertoni Elke Hansel Sybill Moser (4 rows affected) 1> 2> drop table department 3> drop table employee 4> drop table works_on 5> GO 1> 2>
</source>
NOT EXISTS function
<source lang="sql">
1> 2> CREATE TABLE employee (emp_no INTEGER NOT NULL, 3> emp_fname CHAR(20) NOT NULL, 4> emp_lname CHAR(20) NOT NULL, 5> dept_no CHAR(4) NULL) 6> 7> insert into employee values(1, "Matthew", "Smith", "d3") 8> insert into employee values(2, "Ann", "Jones", "d3") 9> insert into employee values(3, "John", "Barrimore","d1") 10> insert into employee values(4, "James", "James", "d2") 11> insert into employee values(5, "Elsa", "Bertoni", "d2") 12> insert into employee values(6, "Elke", "Hansel", "d2") 13> insert into employee values(7, "Sybill", "Moser", "d1") 14> 15> select * from employee 16> GO (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) emp_no emp_fname emp_lname dept_no
-------------------- -------------------- -------
1 Matthew Smith d3
2 Ann Jones d3
3 John Barrimore d1
4 James James d2
5 Elsa Bertoni d2
6 Elke Hansel d2
7 Sybill Moser d1
(7 rows affected) 1> 2> 3> CREATE TABLE department(dept_no CHAR(4) NOT NULL, 4> dept_name CHAR(25) NOT NULL, 5> location CHAR(30) NULL) 6> 7> insert into department values ("d1", "developer", "Dallas") 8> insert into department values ("d2", "tester", "Seattle") 9> insert into department values ("d3", "marketing", "Dallas") 10> 11> select * from department 12> GO (1 rows affected) (1 rows affected) (1 rows affected) dept_no dept_name location
------------------------- ------------------------------
d1 developer Dallas d2 tester Seattle d3 marketing Dallas (3 rows affected) 1> 2> -- NOT EXISTS function. 3> 4> SELECT emp_lname FROM employee WHERE NOT EXISTS 5> (SELECT * FROM department WHERE employee.dept_no = department.dept_no 6> AND location = "Seattle") 7> GO emp_lname
Smith Jones Barrimore Moser (4 rows affected) 1> 2> drop table employee 3> drop table department 4> GO 1> 2>
</source>
Use NOT EXISTS to represent the ALL operator
<source lang="sql">
26> 27> CREATE TABLE employee (emp_no INTEGER NOT NULL, 28> emp_fname CHAR(20) NOT NULL, 29> emp_lname CHAR(20) NOT NULL, 30> dept_no CHAR(4) NULL) 31> 32> insert into employee values(1, "Matthew", "Smith", "d3") 33> insert into employee values(2, "Ann", "Jones", "d3") 34> insert into employee values(3, "John", "Barrimore","d1") 35> insert into employee values(4, "James", "James", "d2") 36> insert into employee values(5, "Elsa", "Bertoni", "d2") 37> insert into employee values(6, "Elke", "Hansel", "d2") 38> insert into employee values(7, "Sybill", "Moser", "d1") 39> 40> select * from employee 41> GO (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) emp_no emp_fname emp_lname dept_no
-------------------- -------------------- -------
1 Matthew Smith d3
2 Ann Jones d3
3 John Barrimore d1
4 James James d2
5 Elsa Bertoni d2
6 Elke Hansel d2
7 Sybill Moser d1
(7 rows affected) 1> 2> CREATE TABLE works_on (emp_no INTEGER NOT NULL, 3> project_no CHAR(4) NOT NULL, 4> job CHAR (15) NULL, 5> enter_date DATETIME NULL) 6> 7> insert into works_on values (1, "p1", "analyst", "1997.10.1") 8> insert into works_on values (1, "p3", "manager", "1999.1.1") 9> insert into works_on values (2, "p2", "clerk", "1998.2.15") 10> insert into works_on values (2, "p2", NULL, "1998.6.1") 11> insert into works_on values (3, "p2", NULL, "1997.12.15") 12> insert into works_on values (4, "p3", "analyst", "1998.10.15") 13> insert into works_on values (5, "p1", "manager", "1998.4.15") 14> insert into works_on values (6, "p1", NULL, "1998.8.1") 15> insert into works_on values (7, "p2", "clerk", "1999.2.1") 16> insert into works_on values (8, "p3", "clerk", "1997.11.15") 17> insert into works_on values (7, "p1", "clerk", "1998.1.4") 18> 19> select * from works_on 20> GO (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) emp_no project_no job enter_date
---------- --------------- -----------------------
1 p1 analyst 1997-10-01 00:00:00.000
1 p3 manager 1999-01-01 00:00:00.000
2 p2 clerk 1998-02-15 00:00:00.000
2 p2 NULL 1998-06-01 00:00:00.000
3 p2 NULL 1997-12-15 00:00:00.000
4 p3 analyst 1998-10-15 00:00:00.000
5 p1 manager 1998-04-15 00:00:00.000
6 p1 NULL 1998-08-01 00:00:00.000
7 p2 clerk 1999-02-01 00:00:00.000
8 p3 clerk 1997-11-15 00:00:00.000
7 p1 clerk 1998-01-04 00:00:00.000
(11 rows affected) 1> --Use NOT EXISTS to represent the ALL operator. 2> 3> SELECT DISTINCT job FROM works_on WHERE NOT EXISTS 4> (SELECT * FROM employee WHERE works_on.emp_no > employee.emp_no) 5> GO job
analyst manager (2 rows affected) 1> 2> drop table works_on 3> drop table employee 4> GO 1> 2>
</source>
Using EXISTS Operator for a subquery
<source lang="sql">
1> 2> create table employee( 3> ID int, 4> name nvarchar (10), 5> salary int ) 6> GO 1> 2> create table job( 3> ID int, 4> title nvarchar (10), 5> averageSalary int) 6> GO 1> 2> 3> insert into employee (ID, name, salary) values (1, "Jason", 1234) 4> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (2, "Robert", 4321) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (3, "Celia", 5432) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (4, "Linda", 3456) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (5, "David", 7654) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (6, "James", 4567) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (7, "Alison", 8744) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (8, "Chris", 9875) 2> GO (1 rows affected) 1> insert into employee (ID, name, salary) values (9, "Mary", 2345) 2> GO (1 rows affected) 1> 2> insert into job(ID, title, averageSalary) values(1,"Developer",3000) 3> GO (1 rows affected) 1> insert into job(ID, title, averageSalary) values(2,"Tester", 4000) 2> GO (1 rows affected) 1> insert into job(ID, title, averageSalary) values(3,"Designer", 5000) 2> GO (1 rows affected) 1> insert into job(ID, title, averageSalary) values(4,"Programmer", 6000) 2> GO (1 rows affected) 1> 2> 3> select * from employee; 4> GO ID name salary
---------- -----------
1 Jason 1234
2 Robert 4321
3 Celia 5432
4 Linda 3456
5 David 7654
6 James 4567
7 Alison 8744
8 Chris 9875
9 Mary 2345
(9 rows affected) 1> select * from job; 2> GO ID title averageSalary
---------- -------------
1 Developer 3000
2 Tester 4000
3 Designer 5000
4 Programmer 6000
(4 rows affected) 1> 2> 3> -- The EXISTS Operator 4> 5> SELECT ID, Name 6> FROM Employee e 7> WHERE NOT EXISTS 8> (SELECT ID 9> FROM job j 10> WHERE j.ID = e.ID) 11> GO ID Name
----------
5 David
6 James
7 Alison
8 Chris
9 Mary
(5 rows affected) 1> 2> drop table employee; 3> drop table job; 4> GO 1> 2>
</source>
