1. SQL Data Definition Language (DDL) Using Microsoft SQL Server 1SDL Data Definition Language (DDL)

2. Data definition language SQL – Structured Query Language – ISO / ANSI standard Microsoft has its own dialect of SQL, called T-SQL – SQL = DDL + DML DDL = Data Definition Language – A part of SQL – Used to create objects in the database Database, table, view, procedure, function, etc. – General syntax Create object_type object_name Create table someName … Alter table someName Drop table someName 2SDL Data Definition Language (DDL)

3. Create table general syntax Create table someName( firstColumn datatype constraints, secondColumn datatype constraints, …. ) – http://msdn.microsoft.com/en- US/library/ms174979%28v=SQL.105%29.aspx http://msdn.microsoft.com/en- US/library/ms174979%28v=SQL.105%29.aspx 3SDL Data Definition Language (DDL)

4. Some data types for use in tables Integers – Bit, Bigint, Int, SmallInt, TinyInt Other numbers – Decimal/Numeric, Float Money – Money, SmallMoney Date and time – DateTime, DataTime2, SmallDateTime, DateTimeOffset, Date, Time Text – Char, VarChar, Text, Nchar, NVarChar, Ntext – VarChar is variable length – Nxx is Unicode Binary data: Pictures, etc. – Binary, VarBinary XML – XML 4SDL Data Definition Language (DDL)

5. Special data types Default – The field has a default value – Used if the user does not supply any data in the INSERT statement Identity – Used to generate number – Usually for generation of primary key values – Works with int and bigint Null / not null – Where null is allowed (or not) for the field Computed columns 5SDL Data Definition Language (DDL)

6. Drop table Deletes an existing table – All the data will be deleted as well! – No possible if other tables are referring (foreign keys) the deleted table – http://msdn.microsoft.com/en- us/library/ms173790.aspx http://msdn.microsoft.com/en- us/library/ms173790.aspx 6SDL Data Definition Language (DDL)

7. Alter table Used to change and existing table – Add / remove columns – Add / remove constraints Fairly complex syntax – http://msdn.microsoft.com/en- us/library/ms190273.aspx http://msdn.microsoft.com/en- us/library/ms190273.aspx – If the table is empty it might be easier to drop an re-create the table 7SDL Data Definition Language (DDL)

8. Naming object in the database General syntax – serverName.DatabaseName.SchemaName.ObjectName ServerName – The name of the server, like sqlexpress DatabaseName – Name of database, like BookStore, Students, etc. SchemaName – A database can contain several schemas – Object names must be unique within the schema – Default schema dbo (Database Owner) ObjectName – Name of table, view, procedure, etc. 8SDL Data Definition Language (DDL)

9. Using the GUI Tool Management Studio has a GUI tool for creating, altering and dropping table, etc. – Create the tables with relevant columns – Create a database diagram – Use the diagram to create foreign key relationships SDL Data Definition Language (DDL)9