8.6.17 getColumns(String catalog, String schemaPattern, String tableNamePattern, String columnNamePattern) : Hitachi Advanced Database Application Development Guide

(1) Function

This method acquires information about table columns.

The information about table columns that can be acquired depends on the privileges of the HADB user who executes this method. For details about the privileges and the table column information that can be acquired, see the topic Scope of information in dictionary tables and system tables that can be referenced by HADB users in the HADB Setup and Operation Guide.

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(2) Format

public synchronized ResultSet getColumns(String catalog, String schemaPattern, String tableNamePattern, String columnNamePattern) throws SQLException

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(3) Arguments

String catalog: Specifies a catalog name. This argument is ignored, if specified.
String schemaPattern: Specifies a schema name pattern^#. This value is case sensitive.
String tableNamePattern: Specifies a table name pattern^#. This value is case sensitive.
String columnNamePattern: Specifies a column name pattern^#. This value is case sensitive.
#: For details about the special characters that can be specified in each pattern, see (4) Special characters that can be specified in pattern character strings in 8.6.1 List of the methods in the DatabaseMetaData interface.

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(4) Return value

The method returns a ResultSet object. The following table shows the format of the ResultSet object that is returned.

Table 8‒48: Format of the ResultSet object that is returned (getColumns method)
Column No.	Type	Column name	Description
1	`String`	`TABLE_CAT`	The method always returns a null character string.
2	`String`	`TABLE_SCHEM`	Schema name
3	`String`	`TABLE_NAME`	Table name
4	`String`	`COLUMN_NAME`	Column name
5	`int`	`DATA_TYPE`	SQL type
6	`String`	`TYPE_NAME`	Type name
7	`int`	`COLUMN_SIZE`	Column size
8	`int`	`BUFFER_LENGTH`	The null value is always returned.
9	`int`	`DECIMAL_DIGITS`	Decimal places
10	`int`	`NUM_PREC_RADIX`	Radix Approximate value: `2` Exact numeric value: `10` Non-numeric value: `0`
11	`int`	`NULLABLE`	Value indicating whether the `NULL` value is permitted: `columnNoNulls`: The null value might not be permitted. `columnNullable`: The null value can be used.
12	`String`	`REMARKS`	Comment column The method always returns a null character string.
13	`String`	`COLUMN_DEF`	The default value of the column is returned. If the returned value is enclosed by single quotation marks (`'`), it means that the default value is a character string. If `NULL` is specified as the default value of the column, the character string `NULL` is returned without single quotation marks (`'`). If no default value is specified for the column, a null value is returned. For details about other return values, see the description of the `DEFAULT_VALUE` column in the table Content of SQL_COLUMNS in the HADB Setup and Operation Guide.
14	`int`	`SQL_DATA_TYPE`	The null value is always returned.
15	`int`	`SQL_DATETIME_SUB`	The null value is always returned.
16	`int`	`CHAR_OCTET_LENGTH`	Maximum length (in bytes) of a `CHAR`-type column
17	`int`	`ORDINAL_POSITION`	Column number (beginning at 1)
18	`String`	`IS_NULLABLE`	Value indicating whether the `NULL` value is permitted: `"NO"`: The null value cannot be used. `"YES"`: The null value might be permitted.
19	`String`	`SCOPE_CATALOG`	The method always returns a null character string.
20	`String`	`SCOPE_SCHEMA`	The method always returns a null character string.
21	`String`	`SCOPE_TABLE`	The method always returns a null character string.
22	`short`	`SOURCE_DATA_TYPE`	The null value is always returned.
23	`String`	`IS_AUTOINCREMENT`	Whether columns are incremented automatically: `NO`: Columns are not incremented automatically. `NO` is always returned.

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(5) Exceptions

If this Connection object is closed before this method is executed, the JDBC driver throws an SQLException.

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(6) Notes

The value acquired as column information of the viewed table might differ between the following two methods:

The DECIMAL_DIGITS value of the ResultSet object acquired by this method
The value acquired by the getScale method of the ResultSetMetaData interface

The first of these methods acquires the scaling value that was in effect when the viewed table was defined. The second of these methods acquires the scaling value that was in effect when the viewed table was retrieved. These two values will differ if the value specified for the adb_sql_prep_dec_div_rs_prior operand in the server definition or the client definition when the table was defined differs from the value specified in this operand when the table was retrieved.

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