BOOLEAN data type


Informix supports the BOOLEAN data type, which can store 't' or 'f' values.

Genero BDL implements the BOOLEAN data type in a different way: A BOOLEAN variable stores integer values 1 or 0 (for TRUE or FALSE). This type is designed to hold the result of a boolean expression.


Oracle 23c supports a native BOOLEAN type in the SQL language. Older Oracle versions like 21c only support a BOOLEAN type in the PL/SQL language.

Note that '1' and '0' char constants are casted by Oracle SQL as BOOLEAN TRUE/FALSE equivalents.


When using dbmora_18 + Oracle client 18c, 19c, 21c or dbmora_23 + Oracle client 23c with an Oracle server version prior to 23c (without SQL BOOLEAN support), the ODI driver will always use CHAR(1) to store FGL BOOLEAN values. The BOOLEAN/CHAR(1) type name conversion in DDL statements can be disabled with the following FGLPROFILE entry:
dbi.database.dsname.ifxemul.datatype.boolean = false
However, SQL parameter and SQL fetch buffers can still be FGL BOOLEAN variables: These are mapped to '1' and '0' values for CHAR(1) columns.
When using dbmora_23 + Oracle client 23c with an Oracle 23c server (and future versions), the ODI driver will by default use the native Oracle SQL BOOLEAN type for FGL BOOLEAN. To get the former behavior BOOLEAN/CHAR(1) conversion, use the following FGLPROFILE entry:
dbi.database.dsname.ora.boolean.aschar = true
In this case, the dbi.database.dsname.ifxemul and dbi.database.dsname.ifxemul.datatype.boolean settings must be left unset or set to true, to create CHAR(1) columns for BOOLEAN in DDL statements. If the Informix emulation settings for boolean is disabled, the use of BOOLEAN type in DDL statements will be accepted by Oracle 23c. However, the ODI driver will use CHAR(1) for SQL Parameter and fetch buffer bindings, and '1'/'0' values.

The BOOLEAN/CHAR(1) conversion rule applies to all SQL tables for a given SQL connection. If you have existing boolean data in several tables using CHAR(1) columns, you need to plan for an upgrade process in order to use the new native SQL BOOLEAN type of Oracle.

Note that the combination of dbmora_18 + Oracle client 18c and Oracle server 23c is possible, but is not supported by Genero: To connect to Oracler 23c server, use dbmora_23 + Oracle client 23c.

When using the BOOLEAN as CHAR(1) emulation, the CONSTRUCT dialog will produce '1' and '0' constants for BOOLEAN fields. When using the native Oracle 23c SQL BOOLEAN type, CONSTRUCT will produce SQL conditions using TRUE and FALSE constants.

To extract database schemas, the fgldbsch tool will do the following:

  • When connecting to an Oracle server of a version prior to 23c, no BOOLEAN type is possible in SQL tables, and CHAR(1) will be seen as CHAR(1) in the resulting .sch file.

  • When connecting to an Oracle 23c server (and future versions), BOOLEAN SQL typed columns will be extracted as FGL BOOLEAN type (45) by default, or as FGL CHAR(1) when using conversion option B. Here option B make only sense for legacy code where boolean values are handled with FGL CHAR(1) variables, assuming '1'/'0' values.

The BOOLEAN type translation can be controlled with the following FGLPROFILE entry:
dbi.database.dsname.ifxemul.datatype.boolean = { true | false }
For more details see IBM Informix emulation parameters in FGLPROFILE.