Adding, inserting or deleting fields

Fields are what hold the actual record data for each row in a table. Whereas a record could be considered a “row” in a table, a field could be considered a “column” in a table, or a “cell” in a record. The fields are defined at the time of the table creation.

Fields are added to the record definition in the order they are declared. The c-treeDB API also includes a set of functions that will allow a field to be inserted at a certain place in the record definition and fields can also be deleted from the record definition.

CTTable::AddField() method will add a new field to the end of the record definition.

// create a new table object

CTTable ATable(ADatabase);

// add two fields to the table record definition

ATAble.AddField(“Field1”, CT_INTEGER, 4);

ATable.AddField(“Field2”, CT_CHAR, 30);

// create the table

ATable.Create(“MyTable”, CTCREATE_NORMAL);

CTTable::InsField() inserts a new field before a given field that has already been defined. CTTable::InsField() overloaded methods allow you to specify a field index or a field name to identify the position on the record definition that the new field will be inserted. The first field is number 0, the second field is number 1 and so on.

// create a new table object

CTTable ATable(ADatabase);

// add two fields to the table record definition

ATable.AddField( “Field1”, CT_INTEGER, 4);

ATable.AddField( “Field2”, CT_CHAR, 30);

ATable.InsField(“Field2”, “Field3”, CT_BOOL, 1);

// create the table

ATable.Create(“MyTable”, CTCREATE_NORMAL);

CTTable::DelField() deletes a field from the record definition. CTTable::DelField() overloaded methods allow the user to specify a field index or a field name to identify the field to delete. The first field is number 0, the second field is number 1, and so on.

// create a new table object

CTTable ATable(ADatabase);

// add two fields to the table record definition

ATable.AddField( “Field1”, CT_INTEGER, 4);

ATable.AddField( “Field2”, CT_CHAR, 30);

// delete field2 from record definition

ATable.DelField(“Field2”);

// create the table

ATable.Create(“MyTable”, CTCREATE_NORMAL);