HP c-tree-SQL ISQL and Tools manual Locking Tutorial, ISQLTutorial3.sql

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Quick Tour

2.3LOCKING TUTORIAL

iSQL_Tutorial3.sql

This tutorial will introduce the concept of locking. The function- ality for this tutorial focuses on adding records, then updating a single record to the customer master table. From the iSQL utility

the script will be parsed and passed to the server. The script com- pletes without "committing" the update. This leaves the updated record locked. The user will launch another instance of the Inter- active SQL utility in another window which will block, waiting on

the lock held by the first instance. Typing "COMMIT WORK;" from the first instance of the iSQL utility will complete the update transaction and remove the lock. This will allow the sec- ond instance to continue execution. Launching two processes provides a visual demonstration of the effects of locking and a basis for experimentation on your own.

It is important to note that locking is inherent at the SQL level. This means that when one pro- cess has a record selected for update, it is locked even though there is no explicit SQL syntax.

This tutorial operates on the assumption that the database named 'myDatabase', already exists. Please refer to Section 3.6 “Introduction to the c-treeSQL ISQL Utility” in c-tree Plus Quick Start and Product Overview Guide for details on how to set up the environment for the tutorial.

This example, like all others in this set of documentation, will take the creation and use of a database and fit it into a simple four step flow of initialization, definition, management, and completion. (Init, define, manage, and you're done!)

Now let's break into the four areas.

2.3.1Init

The initialize step is as simple as launching the iSQL tool. The syntax for this is as follows:

isql [-u user_name] [-a password] [connect_string]

At the command line prompt type:

isql -u ADMIN -a ADMIN myDatabase

iSQL responds with the following prompt:

ISQL>

At this point, any valid SQL statement terminated with a semi-colon may be submitted.

FairCom Corporation

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Contents For use with c-treeSQL Server Isql and Tools Reference GuidePage Table of Contents Data Load Utility dbload Iii Tutorial Source CodeFairCom Corporation Audience Syntax Diagram ConventionsDocumentation Overview Purpose of this ManualIsql and Tools Related DocumentationOverview IntroductionIsql and Tools FairCom Corporation Isql Quick TourIntroductory Tutorial InitIsql Commit Work Custmast DefineManage Isql Create Table CustmastComplete Introductory Tutorial Code DoneQuick Tour ISQLTutorial2.sql Relational Model and Indexing TutorialQuick Tour Values Insert Into Insert IntoValues QTY Price Commit WorkComplete Relational Model and Indexing Tutorial Source Code ISQLTutorial3.sql Locking Tutorial@ISQL @iSQLTutorial3.sql Isql Delete from Custmast Complete Locking Tutorial Source Code ISQLTutorial4.sql Transaction Processing TutorialTransaction Rollback Work Complete Transaction Processing Tutorial Source Code Arguments Isql StatementsStarting Interactive SQL SyntaxConnectstring PasswordStatement History Support UsernameStatement Summary Formatting Output of Isql QueriesIsql Statements Isql Statements for Statement History SupportDisplay Isql Statements for Query Formatting SummaryCustomername Customercity Orderid Ordervalue Example 3-1 Unformatted Query Display from IsqlExample 3-2 Controlling Display Width of Character Columns Formatting Column Display with the Column StatementOrdervalue Example 3-3 Customizing Format of Numeric Column DisplaysCustomername Customercity Example 3-4 Specifying Column Breaks and Values with Display Numorders Customername Example 3-6 Specifying a Query Header and Footer with Title Transaction Support Help and Table StatementsExample Isql Reference1 @ Execute Syntax DescriptionBreakspec Break SyntaxSkip n ExamplesCustomername History Clear SyntaxBreak Column Compute Display Title ArgumentColumn Syntax OptionFormat formatstring ColumnnameHeading headingtext Character Description Date-Time Format Strings for the Column StatementNot Null INT Null ? Type Length ColnameChar Amount OrderinfoSysdate Compute FLDColumn Title NEW TitleVariablename AVG MAX MIN SUM CountValue Define Syntax@columnname ColpositionDisplayvalue COL columnnumberEdit Syntax Related Statements Exit or Quit SyntaxExit Isql GET query.sql 10 GET SyntaxIsql RUN Orderstate Lotlocation Help CommandsclausesHelp Syntax History SyntaxFollowing example illustrates usage of the History statement Host or SH or Syntax HostcommandFrom List Syntax Isql History Quit or Exit Syntax16 RUN Syntax QuitLinesize Save Syntax18 SET Syntax PagesizePagesize numberlines TBL Connection databasename DefaultTransaction Isolation Level isolationlevel Isql Break on Isql Select TBL from Systables TBLShow Syntax Database Connections Is Default ?Spool Syntax Filename onIsql Spool OFF Start SyntaxArgument … Isql Spool STK onNot Null Varchar Null ? Type Length Colname Not Null INTType Length Colname Null ? TablenameDate Double Title SyntaxLeft Center Right COL n TextIsql Clear Title Isql and Tools FairCom Corporation Introduction Data Load Utility dbloadOptions Dbload Command Line SyntaxCommandsfile Prerequisites for DbloadData Load Utility dbload Data File FormatsNext Record Commands FileVariable Length Records Fixed Length RecordsChar Short Long Float Double Define Record StatementNull For Each StatementExamples Example 4-1 Sample dbload commands filesRecord name redefined Compilation ErrorsPosition not specified for fixed length record Fatal Errors Isql and Tools FairCom Corporation Prerequisites for Dbdump Data Unload Utility dbdumpDbdump Command Line Syntax Short Long Float Double Data Unload Utility dbdumpFor Record Statement Define Record custrec of Fixed Length 37 AS Isql and Tools FairCom Corporation Schema Export Utility dbschema Username.triggername Username.procedurenameOutfile Username.tablenameEND Schema Export Utility dbschemaDbschema Import BeginIsql and Tools FairCom Corporation Commit Work Select * from Custmast Delete from Custmast Tutorial Source CodeMoney IntegerVARCHAR6 Commit Work Delete from Custmast Tutorial Source CodeImdesc VARCHAR48 Select * from orderlist Select * from orderitems Isql and Tools FairCom Corporation Index-i SymbolsIndex-ii FairCom Corporation IsqlIndex-iii FairCom Corporation Index