diff -r 4816d766a08a -r f345bda72bc4 Symbian3/PDK/Source/GUID-C474376E-1766-5781-B5BF-3786C5B4D72E.dita --- a/Symbian3/PDK/Source/GUID-C474376E-1766-5781-B5BF-3786C5B4D72E.dita Tue Mar 30 11:42:04 2010 +0100 +++ b/Symbian3/PDK/Source/GUID-C474376E-1766-5781-B5BF-3786C5B4D72E.dita Tue Mar 30 11:56:28 2010 +0100 @@ -1,12 +1,43 @@ - - - - - -Performing Scalar Queries

This tutorial describes the way in which you can execute scalar queries.

Introduction

A scalar query is a SELECT statement which refers to several data fields and returns a single result, for example, a COUNT query on a database column. This gives the number of records in the database. Symbian OS provides a class TSqlScalarFullSelectQuery, for making scalar queries. This is more efficient than the RSqlStatement class.

Basic procedure

The high level steps to perform scalar queries are shown here:

  1. Declare the necessary variables.

  2. Execute the query string.

Detailed steps

To make a scalar query, do the following:

Declare the necessary variables

  1. Instantiate an object of the database class.

    RSqlDatabase myDatabase;

  2. Declare a literal to hold the query string

    _LIT(kQueryString,"SELECT COUNT (*) FROM myTable");

  3. Instantiate an object of the TSqlScalarFullSelectQuery class. This class has a peculiar feature of instantiating an instance of it with a parameter that refers to the database to be queried. The class supplies a number of functions taking SELECT statements as parameters.

    TSqlScalarFullSelectQuery myFullSelectQuery(myDatabase);

Execute the query

See also

Querying a Database

Inserting a Row into a Table

Deleting Rows from a Table

Reading to a Buffer

Reading to Memory

Reading to a Data Stream

Writing to a Data Stream

Performing Scalar Queries - This document

\ No newline at end of file + + + + + +Performing +Scalar QueriesThis tutorial describes the way in which you can execute scalar +queries. +
Introduction

A +scalar query is a SELECT statement which refers to several +data fields and returns a single result, for example, a COUNT query +on a database column. This gives the number of records in the database. Symbian +platform provides a class TSqlScalarFullSelectQuery, for +making scalar queries. This is more efficient than the RSqlStatement class.

+
Basic procedure

The +high level steps to perform scalar queries are shown here:

    +

  1. Declare the necessary +variables.

    2. +

  2. Execute the query string.

    3. +
+
Detailed steps

To +make a scalar query, do the following:

Declare +the necessary variables

    +

  1. Instantiate an object +of the database class.

    RSqlDatabase myDatabase;
    2. +

  2. Declare a literal to +hold the query string

    _LIT(kQueryString,"SELECT COUNT (*) FROM myTable");
    3. +

  3. Instantiate an object +of the TSqlScalarFullSelectQuery class. This class has +a peculiar feature of instantiating an instance of it with a parameter that +refers to the database to be queried. The class supplies a number of functions +taking SELECT statements as parameters.

    TSqlScalarFullSelectQuery myFullSelectQuery(myDatabase);
    4. +

Execute +the query

Execute the query

TInt recCount = myFullSelectQuery.SelectIntL(kQueryString));
+
See also

Querying a Database

Inserting a Row into a Table

Deleting Rows from a Table

Reading to a Buffer

Reading to Memory

Reading to a Data Stream

Writing to a Data Stream

Performing +Scalar Queries - This document

+ \ No newline at end of file