Access Mode

From InterBase

Go Up to Specifying SET TRANSACTION Behavior


The access mode parameter specifies the type of access a transaction has for the tables it uses. There are two possible settings:

  • READ ONLY specifies that a transaction can select data from a table, but cannot insert, update, or delete table data.
  • READ WRITE specifies that a transaction can select, insert, update, and delete table data. This is the default setting if none is specified.

InterBase assumes that most transactions both read and write data. When starting a transaction for reading and writing, READ WRITE can be omitted from SET TRANSACTION statement. For example, the following statements start a transaction, t1, for READ WRITE access:

EXEC SQL
SET TRANSACTION NAME t1;
EXEC SQL
SET TRANSACTION NAME t1 READ WRITE;
Tip:
It is good programming practice to specify the access mode of a transaction, even when it is READ WRITE. It makes an application’s source code easier to read and debug because the intentions of the program are clearly spelled out.

Start a transaction for READ ONLY access when you only need to read data. READ ONLY must be specified. For example, the following statement starts a transaction, t1, for read-only access:

EXEC SQL
SET TRANSACTION NAME t1 READ ONLY;

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