SQL Programming
- 2. OverviewStoring SQL Code can be done in text files or objectsScripts are text files independent of any particular database or server.sql files are scriptsObjects are stored as part of a databaseTend to be part of application “back end” to manage and make use of data
- 3. SQL Programming ObjectsViews are predefined SELECT statementsStored Procedures are instructions about completing a taskTriggers are special stored procedures executing automatically if data or an object changesUser-defined Functions are instructions used as part of another statementsDDL is used to create each object
- 4. ViewsA view is a predefined selected statementAlso referred to as a “virtual table”Allows easier access to dataDon’t need to remember all of the joins required to put data togetherAllows data hidingCan limit the rows or columns returnedAllows structure hidingCan hide how data is actually stored
- 5. Creating a ViewDefine the SELECT statementAdd the Data Definition Language statement before the SELECTCREATE VIEW v_TitleWithPublisherASSELECT t.*, pub_name PublisherFROM titles t JOIN publishers pON t.pub_id=p.pub_id
- 6. Using a ViewA view is used in place of a tableCan apply criteria, grouping, sortingSELECT publisher, title, priceFROM v_TitleWithPublisherWHERE price>20ORDER BY title
- 8. Stored ProceduresStored procedures are similar to procedures in other languagesDesigned to complete a particular taskAdd a rowReturn a value or tableAlso referred to as “sproc”Use CREATE, ALTER to code Use Execute (or EXEC) to run
- 9. Simple Stored ProcedureTo get a list of all authors, code a SELECT statement Add a CREATE statement prior to the SELECTCREATE PROC up_GetAuthorsASSELECT *FROM authors
- 11. ParametersParameters are used to send data to a procedure Referred to as arguments in many languagesDefine a name and data typeName starts with ‘@’Parameters can be INPUT or OUTPUTInput parameters are values going into the procedureOutput parameters are values being used outside of the procedure
- 12. Input ParametersCan use value coming into sprocAs part of WHERE clauseWHERE price>@SearchPriceFor value to store in a tableUPDATE titlesSET price=@NewPriceWHERE title_id= @title_id
- 14. Input Parameters - 2Show data before run sprocShow data after run sproc
- 15. Output ParametersOutput parameters are used to return a valueDirection must be specified when define parameterWhen use sproc, must also provide a variable to capture valueIf want average price of all books can use an output parameter
- 17. FunctionsAlso known as user-defined functions, or “udf”Functions return a value for use as part of another statementAlso referred to as ‘In-Line’Sprocs execute as single statementsCan use input parameters if need to pass in a valueParameters enclosed in parenthesesUDF’s don’t have output parameters
- 18. Function ValuesFunctions may return different types of resultsScalar functions return a single value (string, date, integerTable functions return a table (rows and columns)May be single or multiple statements to generate a tableWhen use, need to qualify with where function is (schema)
- 19. Scalar Function
- 20. Table Function