Learningcomputer.com SQL Server 2008 – Introduction to Transact SQL

What is Transact SQL? It is pronounced as Transact SQL or Transact SEQUEL Transact SQL or TSQL is a powerful database language It provides programmatic functionality within the relational databases provided by Microsoft SQL SERVER and Sybase database products It is SQL-92 compliant as set by ANSI (American National Standards Institute) It can be broken down into two main areas DML (Data manipulation language) e.g. SELECT, INSERT.. DDL (Data definition language) e.g. CREATE TABLE, DROP DATABASE..

Sample database AdventureWorks2008 Adventure Works Cycles, the fictitious company on which the database is based on. It primarily sells bicycle and parts The downloads can be found here ectReleases.aspx?ReleaseId= ectReleases.aspx?ReleaseId=16040 I had some issues running the download program and had to run this command from C:\ regsvr32 vbscript.dll After the download, I was able to run this script RestoreAdventureWorks2008.sql. This was found here C:\Program Files\Microsoft SQL Server\100\Tools\Samples – I had to replace value variable to bolded text above

DML statements for today SELECT INSERT UPDATE DELETE

Mighty SELECT statement The SELECT statement forms the core of the SQL database language Most commonly used SQL command by far You use the SELECT statement to select or retrieve rows and columns from database tables It does not make any changes to the underlying data This statement can use a sub-select (sub query) The SELECT statement syntax contains five major clauses, generally constructed as follows

SELECT statement syntax SELECT FROM [WHERE ] [GROUP BY ] [HAVING ] [ORDER BY ]; * Notice the bold code is required

SELECT Example We will be using the Adventureorks2008 sample database for SQL Server Launch SQL Server Management Studio and connect to your local SQL instance Expand the database tab and select Adventureorks2008 Right click and select New Query Type the following SELECT * FROM PERSON.PERSON WHERE LASTNAME='WOOD‘ It should return 87 rows also known as records

A little more on SELECT Lets try SalesOrderHeader table with multiple condition SELECT * FROM SALES.SALESORDERHEADER WHERE TERRITORYID=1 AND ORDERDATE < ' ' Quick way to copy data from one table to another is SELECT INTO. Why would you need this? SELECT * INTO HUMANRESOURCES.EMPLOYEE2 FROM HUMANRESOURCES.EMPLOYEE

SQL Operators Operators are used to limit the number of results from the query. Also they are used for mathematical and logical operations. Here are a few types of operators. Standard Operators: = equal to <>not equal to greater than >= greater than or equal to between used to show between two numbers Logical Operators AND used when both conditions are included OR used when either of the condition is true NOT opposite of the logical value

INSERT statement Inserts one or more new rows into the specified table When you use the VALUES clause, only a single row is inserted. Typically used to insert single row of data. However INSERT can use a sub-select (sub query) to insert multiple records.

INSERT Syntax INSERT INTO table-name [({column-name},...)] VALUES ({literal},...) | select-statement} If you use a sub-select statement, the number of rows inserted equals the number of rows returned by the select statement Makes it easier to manage the permissions in your databases

INSERT Example We will be using the Person.Person table For BusinessEntityID, I had to insert a record into BusinessEntity for referential integrity, more on this later Right click and select New Query Type the following INSERT INTO PERSON.PERSON (BUSINESSENTITYID, PERSONTYPE, NAMESTYLE,FIRSTNAME, LASTNAME, PROMOTION, MODIFIEDDATE) VALUES (20778, 'EM', 0, 'KASH', 'MUGHAL', 0, GETDATE()) This should insert one record into Person table

UPDATE statement This is used to update data in the tables Uses a WHERE clause to seek the rows that need to be updated Can use a sub-select (sub query) to update data from another underlying table In the absence of WHERE clause, all the records are updated Be VERY careful with this one!

UPDATE Syntax In its simplest form, here is the syntax UPDATE tablename SET {column-name = { | NULL}},... [WHERE ] Notice the Where clause is optional (enclosed in []) however I would strongly recommend using it regularly If you use a sub-select statement, the number of rows inserted equals the number of rows returned by the select statement

UPDATE Example We will update the record that we just inserted into Person.Person table Right click and select new query Type the following UPDATE Person.Person SET FirstName='KASHEF' WHERE BusinessEntityID=20778 This will update one record only

And my favorite DELETE statement Used to delete data from tables Like the Update statement uses the WHERE clause to locate the records to delete. In case of No WHERE clause, deletes all the records in the table Be very careful with this one also! Remember there is no Undo or Control + Z in SQL Server!! Funny but TRUE story

DELETE Syntax DELETE FROM {table-name } [WHERE ]; Notice how you do not need * in fact it will give you an error Where clause is optional (enclosed in []) however I would strongly recommend using it regularly Delete statement can use a sub-select (sub query) In the absence of where clause deletes all rows, enough said

DELETE Example Expand the database tab and select AdventureWorks2008 We will delete one row from Person table, the one we inserted earlier Right click and select new query Type the following DELETE FROM PERSON.PERSON WHERE BUSINESSENTITYID=20778

Review SELECT INSERT UPDATE DELETE