Java Doc for DatabaseMetaData.java in  » Database-JDBC-Connection-Pool » mysql-connector-java-5.1.3 » com » mysql » jdbc » Java Source Code / Java DocumentationJava Source Code and Java Documentation

This class provides information about the database as a whole.

Many of the methods here return lists of information in ResultSets. You can use the normal ResultSet methods such as getString and getInt to retrieve the data from these ResultSets. If a given form of metadata is not available, these methods show throw a SQLException.

Some of these methods take arguments that are String patterns. These methods all have names such as fooPattern. Within a pattern String "%" means match any substring of 0 or more characters and "_" means match any one character.

Only privileges matching the column name criteria are returned.

Only column descriptions matching the catalog, schema, table and column name criteria are returned.

Only descriptions matching the schema, procedure and parameter name criteria are returned.

Only procedure descriptions matching the schema and procedure name criteria are returned.

Only table descriptions matching the catalog, schema, table name and type criteria are returned.

If so, the SQL AS clause can be used to provide names for computed columns or to provide alias names for columns as required.

Each column description has the following columns:

1. SCOPE short => actual scope of result
   • bestRowTemporary - very temporary, while using row
   • bestRowTransaction - valid for remainder of current transaction
   • bestRowSession - valid for remainder of current session
2. COLUMN_NAME String => column name
3. DATA_TYPE short => SQL data type from java.sql.Types
4. TYPE_NAME String => Data source dependent type name
5. COLUMN_SIZE int => precision
6. BUFFER_LENGTH int => not used
7. DECIMAL_DIGITS short => scale
8. PSEUDO_COLUMN short => is this a pseudo column like an Oracle ROWID
   • bestRowUnknown - may or may not be pseudo column
   • bestRowNotPseudo - is NOT a pseudo column
   • bestRowPseudo - is a pseudo column

The catalog column is:

1. TABLE_CAT String => catalog name

Only privileges matching the column name criteria are returned. They are ordered by COLUMN_NAME and PRIVILEGE.

Each privilige description has the following columns:

1. TABLE_CAT String => table catalog (may be null)
2. TABLE_SCHEM String => table schema (may be null)
3. TABLE_NAME String => table name
4. COLUMN_NAME String => column name
5. GRANTOR => grantor of access (may be null)
6. GRANTEE String => grantee of access
7. PRIVILEGE String => name of access (SELECT, INSERT, UPDATE, REFRENCES, ...)
8. IS_GRANTABLE String => "YES" if grantee is permitted to grant to others; "NO" if not; null if unknown

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:

1. TABLE_CAT String => table catalog (may be null)
2. TABLE_SCHEM String => table schema (may be null)
3. TABLE_NAME String => table name
4. COLUMN_NAME String => column name
5. DATA_TYPE short => SQL type from java.sql.Types
6. TYPE_NAME String => Data source dependent type name
7. COLUMN_SIZE int => column size. For char or date types this is the maximum number of characters, for numeric or decimal types this is precision.
8. BUFFER_LENGTH is not used.
9. DECIMAL_DIGITS int => the number of fractional digits
10. NUM_PREC_RADIX int => Radix (typically either 10 or 2)
11. NULLABLE int => is NULL allowed?
    • columnNoNulls - might not allow NULL values
    • columnNullable - definitely allows NULL values
    • columnNullableUnknown - nullability unknown
12. REMARKS String => comment describing column (may be null)
13. COLUMN_DEF String => default value (may be null)
14. SQL_DATA_TYPE int => unused
15. SQL_DATETIME_SUB int => unused
16. CHAR_OCTET_LENGTH int => for char types the maximum number of bytes in the column
17. ORDINAL_POSITION int => index of column in table (starting at 1)
18. IS_NULLABLE String => "NO" means column definitely does not allow NULL values; "YES" means the column might allow NULL values. An empty string means nobody knows.

Each foreign key column description has the following columns:

1. PKTABLE_CAT String => primary key table catalog (may be null)
2. PKTABLE_SCHEM String => primary key table schema (may be null)
3. PKTABLE_NAME String => primary key table name
4. PKCOLUMN_NAME String => primary key column name
5. FKTABLE_CAT String => foreign key table catalog (may be null) being exported (may be null)
6. FKTABLE_SCHEM String => foreign key table schema (may be null) being exported (may be null)
7. FKTABLE_NAME String => foreign key table name being exported
8. FKCOLUMN_NAME String => foreign key column name being exported
9. KEY_SEQ short => sequence number within foreign key
10. UPDATE_RULE short => What happens to foreign key when primary is updated:
    • importedKeyCascade - change imported key to agree with primary key update
    • importedKeyRestrict - do not allow update of primary key if it has been imported
    • importedKeySetNull - change imported key to NULL if its primary key has been updated
11. DELETE_RULE short => What happens to the foreign key when primary is deleted.
    • importedKeyCascade - delete rows that import a deleted key
    • importedKeyRestrict - do not allow delete of primary key if it has been imported
    • importedKeySetNull - change imported key to NULL if its primary key has been deleted
12. FK_NAME String => foreign key identifier (may be null)
13. PK_NAME String => primary key identifier (may be null)

Each foreign key column description has the following columns:

1. PKTABLE_CAT String => primary key table catalog (may be null)
2. PKTABLE_SCHEM String => primary key table schema (may be null)
3. PKTABLE_NAME String => primary key table name
4. PKCOLUMN_NAME String => primary key column name
5. FKTABLE_CAT String => foreign key table catalog (may be null) being exported (may be null)
6. FKTABLE_SCHEM String => foreign key table schema (may be null) being exported (may be null)
7. FKTABLE_NAME String => foreign key table name being exported
8. FKCOLUMN_NAME String => foreign key column name being exported
9. KEY_SEQ short => sequence number within foreign key
10. UPDATE_RULE short => What happens to foreign key when primary is updated:
    • importedKeyCascade - change imported key to agree with primary key update
    • importedKeyRestrict - do not allow update of primary key if it has been imported
    • importedKeySetNull - change imported key to NULL if its primary key has been updated
11. DELETE_RULE short => What happens to the foreign key when primary is deleted.
    • importedKeyCascade - delete rows that import a deleted key
    • importedKeyRestrict - do not allow delete of primary key if it has been imported
    • importedKeySetNull - change imported key to NULL if its primary key has been deleted
12. FK_NAME String => foreign key identifier (may be null)
13. PK_NAME String => primary key identifier (may be null)

Each primary key column description has the following columns:

1. PKTABLE_CAT String => primary key table catalog being imported (may be null)
2. PKTABLE_SCHEM String => primary key table schema being imported (may be null)
3. PKTABLE_NAME String => primary key table name being imported
4. PKCOLUMN_NAME String => primary key column name being imported
5. FKTABLE_CAT String => foreign key table catalog (may be null)
6. FKTABLE_SCHEM String => foreign key table schema (may be null)
7. FKTABLE_NAME String => foreign key table name
8. FKCOLUMN_NAME String => foreign key column name
9. KEY_SEQ short => sequence number within foreign key
10. UPDATE_RULE short => What happens to foreign key when primary is updated:
    • importedKeyCascade - change imported key to agree with primary key update
    • importedKeyRestrict - do not allow update of primary key if it has been imported
    • importedKeySetNull - change imported key to NULL if its primary key has been updated
11. DELETE_RULE short => What happens to the foreign key when primary is deleted.
    • importedKeyCascade - delete rows that import a deleted key
    • importedKeyRestrict - do not allow delete of primary key if it has been imported
    • importedKeySetNull - change imported key to NULL if its primary key has been deleted
12. FK_NAME String => foreign key name (may be null)
13. PK_NAME String => primary key name (may be null)

Each index column description has the following columns:

1. TABLE_CAT String => table catalog (may be null)
2. TABLE_SCHEM String => table schema (may be null)
3. TABLE_NAME String => table name
4. NON_UNIQUE boolean => Can index values be non-unique? false when TYPE is tableIndexStatistic
5. INDEX_QUALIFIER String => index catalog (may be null); null when TYPE is tableIndexStatistic
6. INDEX_NAME String => index name; null when TYPE is tableIndexStatistic
7. TYPE short => index type:
   • tableIndexStatistic - this identifies table statistics that are returned in conjuction with a table's index descriptions
   • tableIndexClustered - this is a clustered index
   • tableIndexHashed - this is a hashed index
   • tableIndexOther - this is some other style of index
8. ORDINAL_POSITION short => column sequence number within index; zero when TYPE is tableIndexStatistic
9. COLUMN_NAME String => column name; null when TYPE is tableIndexStatistic
10. ASC_OR_DESC String => column sort sequence, "A" => ascending, "D" => descending, may be null if sort sequence is not supported; null when TYPE is tableIndexStatistic
11. CARDINALITY int => When TYPE is tableIndexStatisic then this is the number of rows in the table; otherwise it is the number of unique values in the index.
12. PAGES int => When TYPE is tableIndexStatisic then this is the number of pages used for the table, otherwise it is the number of pages used for the current index.
13. FILTER_CONDITION String => Filter condition, if any. (may be null)

Each column description has the following columns:

1. TABLE_CAT String => table catalog (may be null)
2. TABLE_SCHEM String => table schema (may be null)
3. TABLE_NAME String => table name
4. COLUMN_NAME String => column name
5. KEY_SEQ short => sequence number within primary key
6. PK_NAME String => primary key name (may be null)

Only descriptions matching the schema, procedure and parameter name criteria are returned. They are ordered by PROCEDURE_SCHEM and PROCEDURE_NAME. Within this, the return value, if any, is first. Next are the parameter descriptions in call order. The column descriptions follow in column number order.

Each row in the ResultSet is a parameter desription or column description with the following fields:

1. PROCEDURE_CAT String => procedure catalog (may be null)
2. PROCEDURE_SCHEM String => procedure schema (may be null)
3. PROCEDURE_NAME String => procedure name
4. COLUMN_NAME String => column/parameter name
5. COLUMN_TYPE Short => kind of column/parameter:
   • procedureColumnUnknown - nobody knows
   • procedureColumnIn - IN parameter
   • procedureColumnInOut - INOUT parameter
   • procedureColumnOut - OUT parameter
   • procedureColumnReturn - procedure return value
   • procedureColumnResult - result column in ResultSet
6. DATA_TYPE short => SQL type from java.sql.Types
7. TYPE_NAME String => SQL type name
8. PRECISION int => precision
9. LENGTH int => length in bytes of data
10. SCALE short => scale
11. RADIX short => radix
12. NULLABLE short => can it contain NULL?
    • procedureNoNulls - does not allow NULL values
    • procedureNullable - allows NULL values
    • procedureNullableUnknown - nullability unknown
13. REMARKS String => comment describing parameter/column

Note: Some databases may not return the column descriptions for a procedure. Additional columns beyond REMARKS can be defined by the database.

Only procedure descriptions matching the schema and procedure name criteria are returned. They are ordered by PROCEDURE_SCHEM, and PROCEDURE_NAME.

Each procedure description has the the following columns:

1. PROCEDURE_CAT String => procedure catalog (may be null)
2. PROCEDURE_SCHEM String => procedure schema (may be null)
3. PROCEDURE_NAME String => procedure name
4. reserved for future use
5. reserved for future use
6. reserved for future use
7. REMARKS String => explanatory comment on the procedure
8. PROCEDURE_TYPE short => kind of procedure:
   • procedureResultUnknown - May return a result
   • procedureNoResult - Does not return a result
   • procedureReturnsResult - Returns a result

The schema column is:

1. TABLE_SCHEM String => schema name

The '_' character represents any single character.

The '%' character represents any sequence of zero or more characters.

Only privileges matching the schema and table name criteria are returned. They are ordered by TABLE_SCHEM, TABLE_NAME, and PRIVILEGE.

Each privilige description has the following columns:

1. TABLE_CAT String => table catalog (may be null)
2. TABLE_SCHEM String => table schema (may be null)
3. TABLE_NAME String => table name
4. COLUMN_NAME String => column name
5. GRANTOR => grantor of access (may be null)
6. GRANTEE String => grantee of access
7. PRIVILEGE String => name of access (SELECT, INSERT, UPDATE, REFRENCES, ...)
8. IS_GRANTABLE String => "YES" if grantee is permitted to grant to others; "NO" if not; null if unknown

The table type is:

1. TABLE_TYPE String => table type. Typical types are "TABLE", "VIEW", "SYSTEM TABLE", "GLOBAL TEMPORARY", "LOCAL TEMPORARY", "ALIAS", "SYNONYM".

Only table descriptions matching the catalog, schema, table name and type criteria are returned. They are ordered by TABLE_TYPE, TABLE_SCHEM and TABLE_NAME.

Each table description has the following columns:

1. TABLE_CAT String => table catalog (may be null)
2. TABLE_SCHEM String => table schema (may be null)
3. TABLE_NAME String => table name
4. TABLE_TYPE String => table type. Typical types are "TABLE", "VIEW", "SYSTEM TABLE", "GLOBAL TEMPORARY", "LOCAL TEMPORARY", "ALIAS", "SYNONYM".
5. REMARKS String => explanatory comment on the table

Note: Some databases may not return information for all tables.

Each type description has the following columns:

1. TYPE_NAME String => Type name
2. DATA_TYPE short => SQL data type from java.sql.Types
3. PRECISION int => maximum precision
4. LITERAL_PREFIX String => prefix used to quote a literal (may be null)
5. LITERAL_SUFFIX String => suffix used to quote a literal (may be null)
6. CREATE_PARAMS String => parameters used in creating the type (may be null)
7. NULLABLE short => can you use NULL for this type?
   • typeNoNulls - does not allow NULL values
   • typeNullable - allows NULL values
   • typeNullableUnknown - nullability unknown
8. CASE_SENSITIVE boolean=> is it case sensitive?
9. SEARCHABLE short => can you use "WHERE" based on this type:
   • typePredNone - No support
   • typePredChar - Only supported with WHERE .. LIKE
   • typePredBasic - Supported except for WHERE .. LIKE
   • typeSearchable - Supported for all WHERE ..
10. UNSIGNED_ATTRIBUTE boolean => is it unsigned?
11. FIXED_PREC_SCALE boolean => can it be a money value?
12. AUTO_INCREMENT boolean => can it be used for an auto-increment value?
13. LOCAL_TYPE_NAME String => localized version of type name (may be null)
14. MINIMUM_SCALE short => minimum scale supported
15. MAXIMUM_SCALE short => maximum scale supported
16. SQL_DATA_TYPE int => unused
17. SQL_DATETIME_SUB int => unused
18. NUM_PREC_RADIX int => usually 2 or 10

Only types matching the catalog, schema, type name and type criteria are returned. They are ordered by DATA_TYPE, TYPE_SCHEM and TYPE_NAME. The type name parameter may be a fully qualified name. In this case, the catalog and schemaPattern parameters are ignored.

Each type description has the following columns:

1. TYPE_CAT String => the type's catalog (may be null)
2. TYPE_SCHEM String => type's schema (may be null)
3. TYPE_NAME String => type name
4. CLASS_NAME String => Java class name
5. DATA_TYPE String => type value defined in java.sql.Types. One of JAVA_OBJECT, STRUCT, or DISTINCT
6. REMARKS String => explanatory comment on the type

Note: If the driver does not support UDTs then an empty result set is returned.

Each column description has the following columns:

1. SCOPE short => is not used
2. COLUMN_NAME String => column name
3. DATA_TYPE short => SQL data type from java.sql.Types
4. TYPE_NAME String => Data source dependent type name
5. COLUMN_SIZE int => precision
6. BUFFER_LENGTH int => length of column value in bytes
7. DECIMAL_DIGITS short => scale
8. PSEUDO_COLUMN short => is this a pseudo column like an Oracle ROWID
   • versionColumnUnknown - may or may not be pseudo column
   • versionColumnNotPseudo - is NOT a pseudo column
   • versionColumnPseudo - is a pseudo column

If so, the SQL AS clause can be used to provide names for computed columns or to provide alias names for columns as required. A JDBC compliant driver always returns true.