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Gets a description of table columns available in the specified catalog.
Only column descriptions matching the catalog, schema, table and column name criteria are returned. They are ordered by TABLE_SCHEM, TABLE_NAME and ORDINAL_POSITION. Each column description has the following columns:
TABLE_CAT
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String
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table catalog (may be null)
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TABLE_SCHEM
|
String
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table schema (may be null)
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TABLE_NAME
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String
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table name
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COLUMN_NAME
|
String
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column name
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DATA_TYPE
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Short
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SQL type from java.sql.Types
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TYPE_NAME
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String
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Data source dependent type name, for a UDT the type name is fully qualified
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COLUMN_SIZE
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Int
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Column size. For char or date types this is the maximum number of characters, for numeric or decimal types this is precision.
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BUFFER_LENGTH
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is not used.
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DECIMAL_DIGITS
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int
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the number of fractional digits
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NUM_PREC_RADIX
|
int
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Radix (typically either 10 or 2)
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NULLABLE
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int
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is NULL allowed?
columnNoNulls - might not allow NULL values
columnNullable - definitely allows NULL values
columnNullableUnknown - nullability unknown
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REMARKS
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String
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comment describing column (may be null)
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COLUMN_DEF
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String
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default value (may be null)
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SQL_DATA_TYPE
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int
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unused
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SQL_DATETIME_SUB
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int
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unused
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CHAR_OCTET_LENGTH
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int
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for char types the maximum number of bytes in the column
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ORDINAL_POSITION
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int
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index of column in table (starting at 1)
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IS_NULLABLE
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String
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"NO" means column definitely does not allow NULL values; "YES" means the column might allow NULL values. An empty string means nobody knows.
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Syntax
getColumns(string catalog,string schemaPattern,string tableNamePattern, string columnNamePattern)
Parameters
catalog
A catalog name; "" retrieves those without a catalog; null means drop catalog name from the selection criteria
schemaPattern
A schema name pattern; "" retrieves those without a schema
tableNamePattern
A table name pattern
columnNamePattern
a column name pattern
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