MySQL Tutorial/Select Query/Alias

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Aliasing the function in select statement

   <source lang="sql">

mysql> mysql> mysql> mysql> CREATE TABLE Employee(

   ->     id            int,
   ->     first_name    VARCHAR(15),
   ->     last_name     VARCHAR(15),
   ->     start_date    DATE,
   ->     end_date      DATE,
   ->     salary        FLOAT(8,2),
   ->     city          VARCHAR(10),
   ->     description   VARCHAR(15)
   -> );

Query OK, 0 rows affected (0.03 sec) mysql> mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->              values (1,"Jason",    "Martin",  "19960725",  "20060725", 1234.56, "Toronto",  "Programmer");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(2,"Alison",   "Mathews",  "19760321", "19860221", 6661.78, "Vancouver","Tester");

Query OK, 1 row affected (0.01 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(3,"James",    "Smith",    "19781212", "19900315", 6544.78, "Vancouver","Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(4,"Celia",    "Rice",     "19821024", "19990421", 2344.78, "Vancouver","Manager");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(5,"Robert",   "Black",    "19840115", "19980808", 2334.78, "Vancouver","Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(6,"Linda",    "Green",    "19870730", "19960104", 4322.78,"New York",  "Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(7,"David",    "Larry",    "19901231", "19980212", 7897.78,"New York",  "Manager");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(8,"James",    "Cat",     "19960917",  "20020415", 1232.78,"Vancouver", "Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> select * from Employee; +------+------------+-----------+------------+------------+---------+-----------+-------------+ | id | first_name | last_name | start_date | end_date | salary | city | description | +------+------------+-----------+------------+------------+---------+-----------+-------------+ | 1 | Jason | Martin | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto | Programmer | | 2 | Alison | Mathews | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester | | 3 | James | Smith | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester | | 4 | Celia | Rice | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager | | 5 | Robert | Black | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester | | 6 | Linda | Green | 1987-07-30 | 1996-01-04 | 4322.78 | New York | Tester | | 7 | David | Larry | 1990-12-31 | 1998-02-12 | 7897.78 | New York | Manager | | 8 | James | Cat | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester | +------+------------+-----------+------------+------------+---------+-----------+-------------+ 8 rows in set (0.00 sec) mysql> mysql> mysql> mysql> SELECT concat(First_Name, " ",Last_Name) AS Name FROM employee; +----------------+ | Name | +----------------+ | Jason Martin | | Alison Mathews | | James Smith | | Celia Rice | | Robert Black | | Linda Green | | David Larry | | James Cat | +----------------+ 8 rows in set (0.00 sec) mysql> mysql> mysql> mysql> mysql> drop table Employee; Query OK, 0 rows affected (0.00 sec) mysql> mysql></source>


Giving the result of column calculation an alias name

   <source lang="sql">

mysql> mysql> CREATE TABLE Topic(

   ->    TopicID     SMALLINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
   ->    Name        VARCHAR(50) NOT NULL,
   ->    InStock     SMALLINT UNSIGNED NOT NULL,
   ->    OnOrder     SMALLINT UNSIGNED NOT NULL,
   ->    Reserved    SMALLINT UNSIGNED NOT NULL,
   ->    Department  ENUM("Classical", "Popular") NOT NULL,
   ->    Category    VARCHAR(20) NOT NULL,
   ->    RowUpdate   TIMESTAMP NOT NULL
   -> );

Query OK, 0 rows affected (0.02 sec) mysql> mysql> mysql> INSERT INTO Topic (Name, InStock, OnOrder, Reserved, Department, Category) VALUES

   ->                   ("Java",          10,      5,       3,        "Popular",    "Rock"),
   ->                   ("JavaScript",    10,      5,       3,        "Classical",  "Opera"),
   ->                   ("C Sharp",       17,      4,       1,        "Popular",    "Jazz"),
   ->                   ("C",             9,       4,       2,        "Classical",  "Dance"),
   ->                   ("C++",           24,      2,       5,        "Classical",  "General"),
   ->                   ("Perl",          16,      6,       8,        "Classical",  "Vocal"),
   ->                   ("Python",        2,       25,      6,        "Popular",    "Blues"),
   ->                   ("Php",           32,      3,       10,       "Popular",    "Jazz"),
   ->                   ("ASP.net",       12,      15,      13,       "Popular",    "Country"),
   ->                   ("VB.net",        5,       20,      10,       "Popular",    "New Age"),
   ->                   ("VC.net",        24,      11,      14,       "Popular",    "New Age"),
   ->                   ("UML",           42,      17,      17,       "Classical",  "General"),
   ->                   ("www.sqle.ru",25,      44,      28,       "Classical",  "Dance"),
   ->                   ("Oracle",        32,      15,      12,       "Classical",  "General"),
   ->                   ("Pl/SQL",        20,      10,      5,        "Classical",  "Opera"),
   ->                   ("Sql Server",    23,      12,      8,        "Classical",  "General");

Query OK, 16 rows affected (0.00 sec) Records: 16 Duplicates: 0 Warnings: 0 mysql> mysql> select * from Topic; +---------+----------------+---------+---------+----------+------------+----------+---------------------+ | TopicID | Name | InStock | OnOrder | Reserved | Department | Category | RowUpdate | +---------+----------------+---------+---------+----------+------------+----------+---------------------+ | 1 | Java | 10 | 5 | 3 | Popular | Rock | 2007-07-23 19:09:48 | | 2 | JavaScript | 10 | 5 | 3 | Classical | Opera | 2007-07-23 19:09:48 | | 3 | C Sharp | 17 | 4 | 1 | Popular | Jazz | 2007-07-23 19:09:48 | | 4 | C | 9 | 4 | 2 | Classical | Dance | 2007-07-23 19:09:48 | | 5 | C++ | 24 | 2 | 5 | Classical | General | 2007-07-23 19:09:48 | | 6 | Perl | 16 | 6 | 8 | Classical | Vocal | 2007-07-23 19:09:48 | | 7 | Python | 2 | 25 | 6 | Popular | Blues | 2007-07-23 19:09:48 | | 8 | Php | 32 | 3 | 10 | Popular | Jazz | 2007-07-23 19:09:48 | | 9 | ASP.net | 12 | 15 | 13 | Popular | Country | 2007-07-23 19:09:48 | | 10 | VB.net | 5 | 20 | 10 | Popular | New Age | 2007-07-23 19:09:48 | | 11 | VC.net | 24 | 11 | 14 | Popular | New Age | 2007-07-23 19:09:48 | | 12 | UML | 42 | 17 | 17 | Classical | General | 2007-07-23 19:09:48 | | 13 | www.sqle.ru | 25 | 44 | 28 | Classical | Dance | 2007-07-23 19:09:48 | | 14 | Oracle | 32 | 15 | 12 | Classical | General | 2007-07-23 19:09:48 | | 15 | Pl/SQL | 20 | 10 | 5 | Classical | Opera | 2007-07-23 19:09:48 | | 16 | Sql Server | 23 | 12 | 8 | Classical | General | 2007-07-23 19:09:48 | +---------+----------------+---------+---------+----------+------------+----------+---------------------+ 16 rows in set (0.00 sec) mysql> mysql> SELECT Name, InStock+OnOrder-Reserved AS Available

   -> FROM Topic
   -> WHERE Name LIKE "%bach%"
   -> ORDER BY Name;

Empty set (0.00 sec) mysql> mysql> drop table Topic; Query OK, 0 rows affected (0.00 sec)</source>


To sort the output by alias

   <source lang="sql">

mysql> mysql> mysql> CREATE TABLE Employee(

   ->     id            int,
   ->     first_name    VARCHAR(15),
   ->     last_name     VARCHAR(15),
   ->     start_date    DATE,
   ->     end_date      DATE,
   ->     salary        FLOAT(8,2),
   ->     city          VARCHAR(10),
   ->     description   VARCHAR(15)
   -> );

Query OK, 0 rows affected (0.03 sec) mysql> mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->              values (1,"Jason",    "Martin",  "19960725",  "20060725", 1234.56, "Toronto",  "Programmer");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(2,"Alison",   "Mathews",  "19760321", "19860221", 6661.78, "Vancouver","Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(3,"James",    "Smith",    "19781212", "19900315", 6544.78, "Vancouver","Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(4,"Celia",    "Rice",     "19821024", "19990421", 2344.78, "Vancouver","Manager");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(5,"Robert",   "Black",    "19840115", "19980808", 2334.78, "Vancouver","Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(6,"Linda",    "Green",    "19870730", "19960104", 4322.78,"New York",  "Tester");

Query OK, 1 row affected (0.02 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(7,"David",    "Larry",    "19901231", "19980212", 7897.78,"New York",  "Manager");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(8,"James",    "Cat",     "19960917",  "20020415", 1232.78,"Vancouver", "Tester");

Query OK, 1 row affected (0.01 sec) mysql> mysql> select * from Employee; +------+------------+-----------+------------+------------+---------+-----------+-------------+ | id | first_name | last_name | start_date | end_date | salary | city | description | +------+------------+-----------+------------+------------+---------+-----------+-------------+ | 1 | Jason | Martin | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto | Programmer | | 2 | Alison | Mathews | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester | | 3 | James | Smith | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester | | 4 | Celia | Rice | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager | | 5 | Robert | Black | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester | | 6 | Linda | Green | 1987-07-30 | 1996-01-04 | 4322.78 | New York | Tester | | 7 | David | Larry | 1990-12-31 | 1998-02-12 | 7897.78 | New York | Manager | | 8 | James | Cat | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester | +------+------------+-----------+------------+------------+---------+-----------+-------------+ 8 rows in set (0.00 sec) mysql> mysql> SELECT first_name, start_date, CURDATE(),

   -> (YEAR(CURDATE())-YEAR(start_date)) - (RIGHT(CURDATE(),5)<RIGHT(start_date,5))
   -> AS YearServed
   -> FROM employee ORDER BY YearServed;

+------------+------------+------------+------------+ | first_name | start_date | CURDATE() | YearServed | +------------+------------+------------+------------+ | Jason | 1996-07-25 | 2007-07-22 | 10 | | James | 1996-09-17 | 2007-07-22 | 10 | | David | 1990-12-31 | 2007-07-22 | 16 | | Linda | 1987-07-30 | 2007-07-22 | 19 | | Robert | 1984-01-15 | 2007-07-22 | 23 | | Celia | 1982-10-24 | 2007-07-22 | 24 | | James | 1978-12-12 | 2007-07-22 | 28 | | Alison | 1976-03-21 | 2007-07-22 | 31 | +------------+------------+------------+------------+ 8 rows in set (0.00 sec) mysql> mysql> mysql> drop table Employee; Query OK, 0 rows affected (0.00 sec) mysql></source>


Use Aliasing in table joins

   <source lang="sql">

mysql> mysql> CREATE TABLE Employee(

   ->     id            int,
   ->     first_name    VARCHAR(15),
   ->     last_name     VARCHAR(15),
   ->     start_date    DATE,
   ->     end_date      DATE,
   ->     salary        FLOAT(8,2),
   ->     city          VARCHAR(10),
   ->     description   VARCHAR(15)
   -> );

Query OK, 0 rows affected (0.01 sec) mysql> mysql> create table job (

   ->   id         int,
   ->   title      VARCHAR(20)
   -> );

Query OK, 0 rows affected (0.03 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->              values (1,"Jason",    "Martin",  "19960725",  "20060725", 1234.56, "Toronto",  "Programmer");

Query OK, 1 row affected (0.02 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(2,"Alison",   "Mathews",  "19760321", "19860221", 6661.78, "Vancouver","Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(3,"James",    "Smith",    "19781212", "19900315", 6544.78, "Vancouver","Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(4,"Celia",    "Rice",     "19821024", "19990421", 2344.78, "Vancouver","Manager");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(5,"Robert",   "Black",    "19840115", "19980808", 2334.78, "Vancouver","Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(6,"Linda",    "Green",    "19870730", "19960104", 4322.78,"New York",  "Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(7,"David",    "Larry",    "19901231", "19980212", 7897.78,"New York",  "Manager");

Query OK, 1 row affected (0.02 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)

   ->               values(8,"James",    "Cat",     "19960917",  "20020415", 1232.78,"Vancouver", "Tester");

Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into job (id, title) values (1,"Tester"); Query OK, 1 row affected (0.01 sec) mysql> insert into job (id, title) values (2,"Accountant"); Query OK, 1 row affected (0.00 sec) mysql> insert into job (id, title) values (3,"Developer"); Query OK, 1 row affected (0.00 sec) mysql> insert into job (id, title) values (4,"Coder"); Query OK, 1 row affected (0.00 sec) mysql> insert into job (id, title) values (5,"Director"); Query OK, 1 row affected (0.00 sec) mysql> insert into job (id, title) values (6,"Mediator"); Query OK, 1 row affected (0.00 sec) mysql> insert into job (id, title) values (7,"Proffessor"); Query OK, 1 row affected (0.00 sec) mysql> insert into job (id, title) values (8,"Programmer"); Query OK, 1 row affected (0.00 sec) mysql> insert into job (id, title) values (9,"Developer"); Query OK, 1 row affected (0.00 sec) mysql> mysql> select * from job; +------+------------+ | id | title | +------+------------+ | 1 | Tester | | 2 | Accountant | | 3 | Developer | | 4 | Coder | | 5 | Director | | 6 | Mediator | | 7 | Proffessor | | 8 | Programmer | | 9 | Developer | +------+------------+ 9 rows in set (0.00 sec) mysql> select * from Employee; +------+------------+-----------+------------+------------+---------+-----------+-------------+ | id | first_name | last_name | start_date | end_date | salary | city | description | +------+------------+-----------+------------+------------+---------+-----------+-------------+ | 1 | Jason | Martin | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto | Programmer | | 2 | Alison | Mathews | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester | | 3 | James | Smith | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester | | 4 | Celia | Rice | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager | | 5 | Robert | Black | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester | | 6 | Linda | Green | 1987-07-30 | 1996-01-04 | 4322.78 | New York | Tester | | 7 | David | Larry | 1990-12-31 | 1998-02-12 | 7897.78 | New York | Manager | | 8 | James | Cat | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester | +------+------------+-----------+------------+------------+---------+-----------+-------------+ 8 rows in set (0.00 sec) mysql> mysql> mysql> mysql> SELECT O.ID from Employee AS O, job AS C

   -> WHERE C.ID = O.ID;

+------+ | ID | +------+ | 1 | | 2 | | 3 | | 4 | | 5 | | 6 | | 7 | | 8 | +------+ 8 rows in set (0.00 sec) mysql> mysql> mysql> drop table job; Query OK, 0 rows affected (0.00 sec) mysql> drop table Employee; Query OK, 0 rows affected (0.00 sec) mysql> mysql></source>