Metadata Questions (FireDAC)

Go Up to FAQ (FireDAC)

This topic contains a list of questions and answers related to the metadata retrieval.

Q1: Is there a method to check if a table exists inside of a database?

A: There are two basic methods:

1)

try
  FDQuery1.Open('select * from tab where 0 = 1');
  Result := True;
except
  on E: EFDDBEngineException do
    if E.Kind = ekObjNotExists then
      Result := False
    else
      raise;
end;

2)

var
  oList: TStrings;
begin
  oList := TStringList.Create;
  try
    FDConnection1.GetTableNames('', '', ATableName, oList, [osMy, osOther, osSystem],
      [tkTable, tkTempTable, tkLocalTable]);
    Result := oList.Count > 0;
  finally
    oList.Free;
  end;
end;

The first one is more optimized.

Q2: For Oracle, is it possible to get the package procedures using TFDMetaInfoQuery?

A: The following code returns a list of procedures for the PACKAGE_NAME Oracle package.

FDMetaInfoQuery1.BaseObjectName := 'PACKAGE_NAME';
FDMetaInfoQuery1.MetaInfoKind := mkProcs;
FDMetaInfoQuery1.Open;

Q3: How can I get index names using TFDMetaInfoQuery?

A: The following code returns a list of indexes for the MY_TAB table.

FDMetaInfoQuery1.ObjectName := 'MY_TAB';
FDMetaInfoQuery1.MetaInfoKind := mkIndexes;
FDMetaInfoQuery1.Open;

Q4: Query Builder, design-time editors and metadata retrieval functions return object names belonging to my current schema, prefixed with schema/catalog name. How can I exclude it?

A: Two options:

• Set AFullName to False in the TFDConnection.GetXxxxName call;
• FireDAC has two general connection definition parameters - MetaDefCatalog and MetaDefSchema. Depending on the DBMS, either or both of them are supported (see FireDAC Database Connectivity for details). If the object belongs to a specified MetaDefCatalog catalog/MetaDefSchema schema, then this catalog/schema name will be excluded from an object name. So, set MetaDefCatalog/MetaDefSchema to your development catalog/schema name if you need to deploy your application to a different catalog/schema.

Q5: I am calling Oracle stored procedure using public synonym, but FireDAC always appends schema name to the stored procedure name. How can I avoid that?

A: FireDAC has two general connection definition parameters - MetaCurCatalog and MetaCurSchema. Depending on the DBMS, either or both of them are supported (see FireDAC Database Connectivity for details). Setting them to '*' will avoid usage of a corresponding name part in a full object name.