FireDAC.Comp.Client.TFDCustomQuery.SQL
Delphi
property SQL: TStrings read GetSQL write SetSQL;
C++
__property System::Classes::TStrings* SQL = {read=GetSQL, write=SetSQL};
Contents
Properties
| Type | Visibility | Source | Unit | Parent |
|---|---|---|---|---|
| property | public | FireDAC.Comp.Client.pas FireDAC.Comp.Client.hpp |
FireDAC.Comp.Client | TFDCustomQuery |
Description
Contains the text of the SQL statement to execute for the query.
Use the SQL property to specify the SQL command that a query will Execute / ExecSQL / Open.
At design time, the SQL property can be edited by invoking the FireDAC Query Editor dialog. For this, double-click the TFDCustomQuery component. The dialog offers a syntax highlighting editor, a query builder, an ability to test the query and other.
The SQL property can contain an SQL command or a "batch" SQL command, consisting of several SQL commands or a block of code written in the server side programming language. To execute a full featured SQL script, use the TFDScript component.
The SQL statement in the SQL property can also contain:
- Parameter markers, following standard SQL-92 syntax conventions. Parameters are created automatically and stored in the Params property, if ResourceOptions.ParamCreate is True. If ParamBindMode is
pbByName, then for all occurrences of the same marker a single item is created in Params. If ParamBindMode ispbByNumber, then one item is created per each marker. - Substitution variable markers. Macros are created automatically and stored in the Macros property, if ResourceOptions.MacroCreate is True.
- Escape sequences. They allow writing DBMS independent SQL commands.
- Conditional substitutions. They allow you to expand an SQL command conditionally, depending on the application defined attributes.
For details, see Preprocessing Command Text.
To improve performance on adding big SQL queries to the property using TStringList methods, surround this code with SQL.BeginUpdate / SQL.EndUpdate.
After filling this property value, the Param collection is filled automatically, if ResourceOptions.ParamCreate is True.
Example
FDQuery1.SQL.BeginUpdate;
try
FDQuery1.SQL.Add('SELECT ...');
FDQuery1.SQL.Add('...');
FDQuery1.SQL.Add('...');
FDQuery1.SQL.Add('WHERE ID = :ID');
finally
FDQuery1.SQL.EndUpdate;
end;
FDQuery1.ParamByName('ID').AsInteger := 100;
FDQuery1.Open;