Butler SQL Reference

Chapter 1 • SQL statement overview Chapter 1 • SQL statement overview The basic SQL unit of execution is the statement. SQL program statements allow you to connect to Butler SQL database servers, manipulate data, control program flow, and retrieve data and descriptive information. About this guide This guide is a reference to the SQL dialect supported by Butler SQL. Statement functional groups are presented, followed by a complete description of each statement. The statements are listed in alphabetical order. Statement groups SQL statements can be divided into the following 4 function groups: • Data-manipulation statements offer complete, SQL-based data access to host databases and files. For example, the UPDATE statement modifies database contents. • Program-control statements support testing, looping, and procedure calls within a SQL program. For example, the WHILE statement provides repeated execution of a SQL loop. • Output-control statements generate output messages from the SQL program for processing by the client application. • Database entity-manipulation statements create and delete databases, tables, and indices. 1 Chapter 1 • SQL statement overview The following sections describe each statement group in detail and list statements that belong to each group. Data-manipulation statements Butler SQL’s data-manipulation facilities provide uniform access to databases and files for data retrieval and update. The data- manipulation statements are based on SQL, which has become a de facto standard for relational database access. An ANSI standard for SQL has been defined; however, many variations in the SQL dialects of current DBMS systems, and large areas of the lan- guage, are left as implementation choices in the current ANSI specification. The variations include the areas of database organi- zation, data types, catalog structures, dynamic query support, buffer management, indicator variable handling, and error codes. The Butler SQL data-manipulation statements adhere to ANSI standard statement syntax wherever possible. Where the ANSI standard is not implemented, Butler SQL follows IBM’s DB2 standard if possible. For example, Butler SQL error codes are compatible with DB2 codes. The SQL statements that provide the data-manipulation facilities of database access, dat…