Difference between revisions of "Using Recital SQL"

Revision as of 12:14, 22 December 2009

Using Recital SQL

Creating a Recital Database

The create database statement is used to create a new database. This will create a sub-directory in the DB_DATADIR directory and a database catalog with the same name as the database specified.

create database [if not exists] <database>

A database, its tables and other associated files can be physically deleted using the drop database statement.

drop database [if exists] <database>

Opening a Recital Database

To open a database and set it as the default database for any subsequent SQL statements, use the open database statement.

open database <database> [EXCLUSIVE | SHARED] [NOUPDATE] [VALIDATE]

The open database command triggers the DBC_OPENDATA database event. If a dbc_opendata.prg program file exists in the database's directory, this will be run. If the dbc_opendata.prg program returns .F. (False), the open database operation will be abandoned.

Databases can also have an associated procedure library that is activated automatically when the database is opened. The procedure library must follow the naming convention dbc_<database>_library.prg and must exist in the database's directory. When the database is closed, the procedure library is also closed.

Recital also supports the MySQL compatible use statement to open a database.

use <database>

Creating a Recital Table using Recital SQL

The create table statement creates a new table in the current database, or a new free table if no database is open.

Table column names, data types and constraints can be defined. Table constraints can also be specified.

create table [if not exists] <table>
  (<column> <datatype> [<column constraint> [...]][,...] [<table constraint> [...]])

Data Types

Recital supports the following data types:

• BIGINT
• BIT
• CHAR
• CURRENCY
• DATE
• DATETIME
• DECIMAL
• DOUBLE
• FLOAT
• GENERAL
• INTEGER
• LOGICAL
• LONG VARCHAR
• LONG VARBINARY
• MEDIUMINT
• MEMO
• NUMERIC
• OBJECT
• REAL
• SHORT
• SMALLINT
• TEXT
• TIME
• TIMESTAMP
• TINYINT
• VARCHAR

Table Constraints

Column Constraints

Example

CREATE TABLE customer;
  (account_no CHAR(5) DESCRIPTION  "Account Code";
  DEFAULT strzero(seqno(),5),;
  title CHAR(3) DESCRIPTION "Personal Title",
  last_name CHAR(16) DESCRIPTION "Customer's Last Name",;
  first_name CHAR(10) DESCRIPTION "Customer's Given Name",;
  initial CHAR(2) DESCRIPTION "Customer's Middle Initial",;
  street CHAR(25) DESCRIPTION "Street Number and Name",;
  city CHAR(12) DESCRIPTION "City",;
  state CHAR(2) DESCRIPTION "State Abbreviation";
  CHECK rlookup(customer.state,state);
  ERROR "Invalid State",;
  zip CHAR(10) DESCRIPTION "Zip Code",;
  limit DECIMAL(11,2) DESCRIPTION "Credit Limit";
  RECALCULATE,;
  balance DECIMAL(11,2) DESCRIPTION "Credit Balance";
  RECALCULATE,;
  available DECIMAL(11,2) DESCRIPTION "Credit Available";
  CALCULATED limit-balance,;
  notes LONG VARCHAR DESCRIPTION "Customer Notes",;
  start_date DATE DESCRIPTION "Customer Start Date";
  DEFAULT date(),;
  ONOPEN "customer")

Loading Metadata from an Array or XML File

The create table statement also allows a new table to be created from metadata stored in an array or an XML file. In addition, data can optionally be loaded from the specified XML file.

create table [if not exists] <table>
  [from] xml <.xml file> [load] | from array <array> 

Example

// Create table from XML file
SELECT * FROM customer;
  SAVE AS XML cust.xml
 
CREATE TABLE customer2;
  FROM XML cust.xml
 
// Create table from array
CREATE TABLE newtable FROM ARRAY meta1

ALTER TABLE

The alter table statement allows columns and constraints in an existing table to be added, modified or dropped.

ALTER [IGNORE] TABLE [<database>!]<table>
ADD [COLUMN] (<column> <datatype> [<column constraints>] [,...]) | <table constraint>
| ALTER | MODIFY [COLUMN] <column> [SET DEFAULT <value> | DROP DEFAULT] | (<column> <datatype> [<column constraint>] [,...])
| CONSTRAINT (<column> SET <column constraint> <value> [,...]) | <table constraint>
| DROP [COLUMN] <column> | (<column> [,...]) | CONSTRAINT (<column> <column constraint> [,...]) | <table constraint>
| SET CHECK <condition> [ERROR <message>]
| RENAME (<column>,<new column>)

• ALTER INDEX
• CREATE INDEX

Inserting Records into a Recital Table using Recital SQL

• INSERT

Selecting Records from a Recital Table Using Recital SQL

• SELECT
• DECLARE CURSOR
• OPEN
• FETCH
• DROP CURSOR

Updating Records in a Recital Table using Recital SQL

• UPDATE
• BEGIN...END TRANSACTION
• COMMIT
• ROLLBACK

Deleting Records in a Recital Table using Recital SQL

• DELETE

Obtain Information about a Recital Table using SQL

• SYSBESTROWIDENTIFIER Description of a table’s optimal set of columns that uniquely identifies a row
• SYSCOLUMNCONSTRAINTS Description of the constraints for a table’s columns
• SYSCOLUMNPRIVILEGES Description of the access rights for a table’s columns
• SYSCOLUMNS Description of the table columns available in the catalog
• SYSCROSSREFERENCE Description of how one table imports the keys of another table
• SYSEXPORTEDKEYS Description of the foreign key columns that reference the primary key columns
• SYSIMPORTEDKEYS Description of the primary key columns that are referenced by the foreign key
• SYSINDEXINFO Description of a table’s indices and statistics
• SYSPRIMARYKEYS Description of the primary key columns in the table
• SYSTABLECONSTRAINTS Description of the constraints for each table available in the catalog
• SYSTABLEPRIVILEGES Description of the access rights for each table available in the catalog
• SYSTABLES Description of the tables available in the catalog
• SYSTABLETYPES Table types available in the database system
• SYSVERSIONCOLUMNS Description of the columns in a table that are automatically updated when any row is updated

Executing Procedures and Prepared Statements using Recital SQL

• CREATE PROCEDURE
• DROP PROCEDURE
• EXECUTE
• EXECUTE IMMEDIATE
• PREPARE
• SYSRESULTSET Used to return the singleton result from any Recital expression

Summary