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Holds all the parameters of a column.
Attribute | Definition |
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name | Required. Holds the column name. The name should follow the naming conventions specified in Naming conventions. |
data-type | Required. Holds the data type of a column: BOOLEAN Does not require data-length or data-scale attributes. These attributes should not be specified. Implementation on all DBMSs:CHAR(1) where T is the boolean TRUE value and F is FALSE .
CHAR Requires data-length attribute. Implementation on all DBMSs:CLOB Requires data-length attribute. Implementation:TEXT for Microsoft SQL ServerCLOB for Oracle
DECIMAL Requires data-length (used for precision) and data-scale attributes. Implementation:NUMBER(data-length, data-scale) for Microsoft SQL Server and IBM UDB Oracle
FLOAT Requires data-length attribute. Implementation:FLOAT(data-length) for Microsoft SQL ServerNUMBER without any parameters for Oracle
INTEGER Requires data-length attribute. Implementation:data-length less than three: TINYINT ; data-length two-to-four: SMALLINT ; data-length more than four: BIGINT for Microsoft SQL ServerNUMBER(data-length) for Oracle
TIMESTAMP Does not require data-length or data-scale attributes. These attributes should not be specified. Implementation:DATETIME for Microsoft SQL ServerTIME for Oracle
UNIQUE INTEGER Does not require data-length or data-scale attributes. These attributes should not be specified. This is a data type for a unique integer whose values are generated automatically. Implementation:IDENTITY for Microsoft SQL ServerNUMBER(20,0) for Oracle. In addition, a SEQUENCE and a TRIGGER BEFORE INSERT are created, which select the NEXTVAL of the SEQUENCE from DUAL .
VARCHAR Requires the data-length attribute. Implementation:VARCHAR(data-length) for Microsoft SQL ServerVARCHAR2(data-length) for Oracle
VARBINARY Requires the data-length attribute. Implementation:VARBINARY(data-length) for Microsoft SQL ServerRAW(data-length) for Oracle
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data-length | Required only for the data types listed below. Specifies the column data length: CHAR CLOB DECIMAL FLOAT INTEGER VARCHAR VARBINARY
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data-scale | Required only for the data type DECIMAL . Specifies the column data scale. |
null | Required. Has the value TRUE if the column is nullable and FALSE if it is not. |
default | Optional. Specifies the column default. Can have the following values: NULL if the column is nullable (null=TRUE).N/A if no default exists. If the attribute is omitted, this is the default.
A constant value that is equal to the column type: BOOLEAN TRUE or FALSE CHAR A textual constant, such as ABC CLOB ; a textual constant, such as ABC DECIMAL ; or a decimal point constant, such as 10.3 FLOAT A floating point constant, such as 12E7 INTEGER An integer constant, such as 27 TIMESTAMP One of the following:- A timestamp constant of the format
yyyy-mm-dd hh:mm:ss.fffffffff , which is jafa.sql.Timestamp’s format, such as 2020-02-20 23:07:35:175000000 . Each DBMS displays a slightly different default. Implementation:2020-02-20 23:07:35:175 for Microsoft SQL ServerTO_DATE('2020-02-20 23:07:35') for Oracle
- The literal string
CURRENT TIMESTAMP . Implementation:GETDATE() for Microsoft SQL ServerSYSDATE for Oracle
UNIQUE INTEGER Default value not required and not allowed.VARCHAR A textual constant, such as ABC VARBINARY A hex string where every two hexadecimal digits represent one byte, such as A07C889F . Each DBMS displays a slightly different default. Implementation:0xA07C889F for Microsoft SQL ServerHEXTORAW('A07C889F') for Oracle
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type | Required for the column role in columns of statistics tables. Can have the following values: IDENTIFIER A column identifying the sampled entity. The concatenation of all identifiers should uniquely identify the entity.DATE A column identifying the sampled period. Its type should be TIMESTAMP and be equal to the beginning of the sampled period.SUM A statistics column whose transfer to a higher summary level (such as hourly to daily) should be applied by the SUM function.MIN A statistics column whose transfer to a higher summary level (such as hourly to daily) should be applied by the MIN function.MAX A statistics column whose transfer to a higher summary level (such as hourly to daily) should be applied by the MAX function.AVG A statistics column whose transfer to a higher summary level (such as hourly to daily) should be applied by the AVG function.
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