Using the TABLESAMPLE to Return Random Rows : TABLESAMPLE « Query « SQL Server / T-SQL Tutorial

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SQL Server / T-SQL Tutorial » Query » TABLESAMPLE 
1.30.1.Using the TABLESAMPLE to Return Random Rows
TABLESAMPLE extracts a sampling of rows from a table in the FROM clause.
This sampling can be based on a percentage of number of rows.


3>
4CREATE TABLE employee(
5>    id          INTEGER NOT NULL PRIMARY KEY,
6>    first_name  VARCHAR(10),
7>    last_name   VARCHAR(10),
8>    salary      DECIMAL(10,2),
9>    start_Date  DATETIME,
10>    region      VARCHAR(10),
11>    city        VARCHAR(20),
12>    managerid   INTEGER
13);
14> GO
1INSERT INTO employee VALUES (1'Jason' ,  'Martin', 5890,'2005-03-22','North','Vancouver',3);
2> GO

(rows affected)
1INSERT INTO employee VALUES (2'Alison',  'Mathews',4789,'2003-07-21','South','Utown',4);
2> GO

(rows affected)
1INSERT INTO employee VALUES (3'James' ,  'Smith',  6678,'2001-12-01','North','Paris',5);
2> GO

(rows affected)
1INSERT INTO employee VALUES (4'Celia' ,  'Rice',   5567,'2006-03-03','South','London',6);
2> GO

(rows affected)
1INSERT INTO employee VALUES (5'Robert',  'Black',  4467,'2004-07-02','East','Newton',7);
2> GO

(rows affected)
1INSERT INTO employee VALUES (6'Linda' ,  'Green' , 6456,'2002-05-19','East','Calgary',8);
2> GO

(rows affected)
1INSERT INTO employee VALUES (7'David' ,  'Larry',  5345,'2008-03-18','West','New York',9);
2> GO

(rows affected)
1INSERT INTO employee VALUES (8'James' ,  'Cat',    4234,'2007-07-17','West','Regina',9);
2> GO

(rows affected)
1INSERT INTO employee VALUES (9'Joan'  ,  'Act',    6123,'2001-04-16','North','Toronto',10);
2> GO

(rows affected)
1>
2select from employee;
3> GO
id          first_name last_name  salary       start_Date              region     city                 managerid
----------- ---------- ---------- ------------ ----------------------- ---------- -------------------- -----------
          Jason      Martin          5890.00 2005-03-22 00:00:00.000 North      Vancouver                      3
          Alison     Mathews         4789.00 2003-07-21 00:00:00.000 South      Utown                          4
          James      Smith           6678.00 2001-12-01 00:00:00.000 North      Paris                          5
          Celia      Rice            5567.00 2006-03-03 00:00:00.000 South      London                         6
          Robert     Black           4467.00 2004-07-02 00:00:00.000 East       Newton                         7
          Linda      Green           6456.00 2002-05-19 00:00:00.000 East       Calgary                        8
          David      Larry           5345.00 2008-03-18 00:00:00.000 West       New York                       9
          James      Cat             4234.00 2007-07-17 00:00:00.000 West       Regina                         9
          Joan       Act             6123.00 2001-04-16 00:00:00.000 North      Toronto                       10

(rows affected)
1>
2>
3SELECT First_Name,Last_Name
4FROM employee TABLESAMPLE SYSTEM (PERCENT)
5> GO
First_Name Last_Name
---------- ----------

(rows affected)
1>
2>
3> drop table employee;
4> GO
1.30.TABLESAMPLE
1.30.1.Using the TABLESAMPLE to Return Random Rows
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