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    CREATETABLE–SQLCommand

    编辑:教程网 来源:网络 时间:2011年08月14日 15:52

    CREATE TABLE – SQL Command

    Creates a table having the specified fields.wwww.iTbulo.comem8Zf

    CREATE TABLE | DBF TableName1 [NAME LongTableName] [FREE]   (FieldName1 FieldType [(nFieldWidth [, nPrecision])]      [NULL | NOT NULL]       [CHECK lExpression1 [ERROR cMessageText1]]      [DEFAULT eExpression1]      [PRIMARY KEY | UNIQUE]      [REFERENCES TableName2 [TAG TagName1]]      [NOCPTRANS]   [, FieldName2 ...]      [, PRIMARY KEY eExpression2 TAG TagName2      |, UNIQUE eExpression3 TAG TagName3]      [, FOREIGN KEY eExpression4 TAG TagName4 [NODUP]         REFERENCES TableName3 [TAG TagName5]]      [, CHECK lExpression2 [ERROR cMessageText2]])| FROM ARRAY ArrayName

    Parameters
    TableName1 Specifies the name of the table to create. The TABLE and DBF options are identical. NAME LongTableName Specifies a long name for the table. A long table name can be specified only when a database is open because long table names are stored in databases.

    Long names can contain up to 128 characters and can be used in place of short file names in the database. wwww.iTbulo.comem8Zf

    FREE Specifies that the table will not be added to an open database. FREE isn't required if a database isn't open. (FieldName1 FieldType [(nFieldWidth [, nPrecision])] Specifies the field name, field type, field width, and field precision (number of decimal places), respectively.

    A single table can contain up to 255 fields. If one or more fields allow null values, the limit is reduced by one to 254 fields.

    FieldType is a single letter indicating the field's data type. Some field data types require that you specify nFieldWidth or nPrecision, or both.

    The following table lists the values for FieldType and whether nFieldWidth and nPrecision are required. wwww.iTbulo.comem8Zf

    FieldTypenFieldWidth nPrecisionDescriptionCn–Character field of width nD––DateT––DateTimeNndNumeric field of width n with d decimal placesFndFloating numeric field of width n with d decimal placesI––IntegerB–dDouble Y––CurrencyL––LogicalM––MemoG––General

    nFieldWidth and nPrecision are ignored for D, T, I, Y, L, M, G, and P types. nPrecision defaults to zero (no decimal places) if nPrecision isn't included for the N or F types. nPrecision defaults to the number of decimal places specified by the SET DECIMAL setting if nPrecision isn't included for the B type. wwww.iTbulo.comem8Zf

    NULL Allows null values in the field. If one or more fields can contain null values, the maximum number of fields the table can contain is reduced by one, from 255 to 254. NOT NULL Prevents null values in the field.
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