The different types of browse available in SQL

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Overview
Comparing the two methods

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SQL functions for accessing the external databases

The different types of browse available in SQL

Overview

Two types of browse can be used to browse the result of a query run by SQLExec

Course type: SQLFirst/SQLCol
Route type: SQLFetch/SQLGetCol.

The following paragraphs present the benefits and the drawbacks of these two methods.

Comparing the two methods

The table below presents the characteristics of the two browsing methods:


	SQLFirst/SQLCol browse	SQLFetch/SQLGetCol browse
Query result	All the records found in the query result are loaded in memory when running SQLFirst. The first call to SQLFirst can be quite long.	No record is loaded in memory. The query result is managed by the database.
Number of records	The number of records corresponding to the query result is automatically calculated when reading the first record (SQLFirst). The SQL.NbLine variable is updated	The number of records corresponding to the query result is not calculated.
SQLInfo	SQLInfo returns information about the query and the current browse.	SQLInfo returns general information about the query or the connection.
Browsing the records	Ability to go back to a previous result element	No ability to go back to a previous result element
	The query result is read by SQLCol, SQLAssociate.	The query result is read by SQLGetCol and SQLGetMemo.
Display in a table	SQLTable must not be used (fatal error).	SQLTable can only be used to retrieve the result records from the current record.
Management of tabulations	This type of browse cannot be used to retrieve the tabulations found in the values of records. A tabulation separates two items. Only the part found before the tabulation will be retrieved by the read functions. For more details, see the help about SQLCol and SQLAssociate.	This type of browse can be used to retrieve the tabulations found in the values of records. For more details, see the help about SQLGetCol.

Example of SQLFirst/SQLCol browse

ResExec = SQLExec("SELECT CUSTNAME FROM INV","QRY1")
IF ResExec THEN 
	SQLFirst("QRY1") 
	// Transfer the name into LIST_NAMELIST
	WHILE NOT SQL.Out
		ListAdd(LIST_NAMELIST, SQLCol("QRY1",1))
		SQLNext("QRY1")
	END
ELSE
	// ProcessError
END
SQLClose("QRY1")

Example of SQLFetch/SQLGetCol browse

i is int = 0
SQLExec("SELECT LASTNAME, FIRSTNAME, EXTENSION, PHOTO FROM CUSTOMER", "QRY1")
// Retrieve the query row by row
WHILE SQLFetch("QRY1") = 0 
	// There is still another line
	i++
	// Retrieve the data
	LASTNAME[i] = SQLGetCol("QRY1", 1)
	FIRSTNAME[i] = SQLGetCol("QRY1", 2)
	EXTENSION[i] = SQLGetCol("QRY1",3)
	{"IMAGE"+i} = SQLGetMemo("QRY1", 4)
END
SQLClose("QRY1")