Platform and Client Compatibility

Many platforms use the database system. External compatibility of the database system provides a lot of convenience for platforms.

convert_string_to_digit

Parameter description: Specifies the implicit conversion priority, which determines whether to preferentially convert strings into numbers.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

Value range: Boolean

• on indicates that strings are preferentially converted into numbers.
• off indicates that strings are not preferentially converted into numbers.

Default value: on

NOTICE: Adjusting this parameter will change the internal data type conversion rule and cause unexpected behavior. Exercise caution when performing this operation.

nls_timestamp_format

Parameter description: Specifies the default timestamp format.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

Value range: a string

Default value: DD-Mon-YYYY HH:MI:SS.FF AM

max_function_args

Parameter description: Specifies the maximum number of parameters allowed for a function.

This parameter is a fixed INTERNAL parameter and cannot be modified.

Value range: an integer.

Default value: 666

transform_null_equals

Parameter description: Specifies whether expressions of the form expr = NULL (or NULL = expr) are treated as expr IS NULL. They return true if expr evaluates to the null value, and false otherwise.

• The correct SQL-standard-compliant behavior of expr = NULL is to always return null (unknown).
• Filtered forms in Microsoft Access generate queries that appear to use expr = NULL to test for null values. If you turn this option on, you can use this interface to access the database.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

Value range: Boolean

• on indicates that expressions of the form expr = NULL (or NULL = expr) are treated as expr IS NULL.
• off indicates that expr = NULL always returns null (unknown).

Default value: off

NOTE: New users are always confused about the semantics of expressions involving NULL values. Therefore, off is used as the default value.

support_extended_features

Parameter description: Specifies whether extended database features are supported.

This parameter is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Value range: Boolean

• on indicates that extended database features are supported.
• off indicates that extended database features are not supported.

Default value: off

sql_compatibility

Parameter description: Specifies the type of mainstream database with which the SQL syntax and statement behavior of the database is compatible. This parameter is an INTERNAL parameter. It can be viewed but cannot be modified.

Value range: enumerated values

• A indicates that the database is compatible with the O database.
• B indicates that the database is compatible with the MY database.
• C indicates that the database is compatible with the TD database.
• PG indicates that the database is compatible with the PostgreSQL database.

Default value: A

NOTICE:

• This parameter can be set only when you run the CREATE DATABASE command to create a database.
• In the database, this parameter must be set to a specific value. It can be set to A or B and cannot be changed randomly. Otherwise, the setting is not consistent with the database behavior.

behavior_compat_options

Parameter description: Specifies database compatibility behavior. Multiple items are separated by commas (,).

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

Value range: a string

Default value: empty

NOTE:

• Currently, only compatibility configuration items in Table 1 are supported.
• Multiple items are separated by commas (,), for example, set behavior_compat_options='end_month_calculate,display_leading_zero';.

Table 1 Compatibility configuration items

postgres=# select add_months('2018-02-28',3) from sys_dummy;
add_months
\---------------------
2018-05-28 00:00:00
(1 row)

postgres=# select add_months('2018-02-28',3) from sys_dummy;
add_months
\---------------------
2018-05-31 00:00:00
(1 row)

postgres=# select length(lpad('123',0,'*')) from sys_dummy;
length
\--------
(1 row)

postgres=# select length(lpad('123',0,'*')) from sys_dummy;
length
-——-
0
(1 row)

td_compatible_truncation

Parameter description: Specifies whether to enable features compatible with a Teradata database. You can set this parameter to on when connecting to a database compatible with the Teradata database, so that when you perform the INSERT operation, overlong strings are truncated based on the allowed maximum length before being inserted into char- and varchar-type columns in the target table. This ensures all data is inserted into the target table without errors reported.

NOTE: The string truncation function cannot be used if the INSERT statement includes a foreign table. If inserting multi-byte character data (such as Chinese characters) to database with the character set byte encoding (such as SQL_ASCII or LATIN1), and the character data crosses the truncation position, the string is truncated based on its bytes instead of characters. Unexpected result will occur in tail after the truncation. If you want correct truncation result, you are advised to adopt encoding set such as UTF8, which has no character data crossing the truncation position.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1.

Value range: Boolean

• on indicates that overlong strings are truncated.
• off indicates that overlong strings are not truncated.

Default value: off