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jixian 2001-07-30
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wo.....cuole
Jpp 2001-07-27
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jixian(极限), 你后面的问题应该另开一贴, 因为你的题目说的清楚: 如何建索引？
不要轻易地违背你的诺言!
不要轻易地违背你的诺言!
jixian 2001-07-27
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如何引用呢？
highw 2001-07-27
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Description
Use the CREATE INDEX statement to create a secondary index for an existing table. Index names may not have embedded spaces. Paradox indexes may be based on multiple columns. Due to the distinctive nature of dBASE expression indexes, only single-column indexes can be created with CREATE INDEX.
Use UNIQUE to create an index that raises an error if rows with duplicate column values are inserted. By default, indexes are not unique.
Use ASC (or ASCENDING) to create an index that orders data in an ascending direction (smallest to largest). DESC (or DESCENDING) creates a descending ordering (largest to smallest). When a direction imperative is not specified, ASC is the implied default.
The following statement creates a multi-column (compound) Paradox secondary index.
CREATE INDEX CustDate ON "Orders.db" (CustNo, SaleDate)
The following statement creates a unique dBASE secondary index.
CREATE UNIQUE INDEX Namex ON "Employee.dbf" (Last_Name)
The existence of indexes may affect the updatability of queries. See the section on updatable queries for more information.
Use the CREATE INDEX statement to create a secondary index for an existing table. Index names may not have embedded spaces. Paradox indexes may be based on multiple columns. Due to the distinctive nature of dBASE expression indexes, only single-column indexes can be created with CREATE INDEX.
Use UNIQUE to create an index that raises an error if rows with duplicate column values are inserted. By default, indexes are not unique.
Use ASC (or ASCENDING) to create an index that orders data in an ascending direction (smallest to largest). DESC (or DESCENDING) creates a descending ordering (largest to smallest). When a direction imperative is not specified, ASC is the implied default.
The following statement creates a multi-column (compound) Paradox secondary index.
CREATE INDEX CustDate ON "Orders.db" (CustNo, SaleDate)
The following statement creates a unique dBASE secondary index.
CREATE UNIQUE INDEX Namex ON "Employee.dbf" (Last_Name)
The existence of indexes may affect the updatability of queries. See the section on updatable queries for more information.
highw 2001-07-27
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CREATE [UNIQUE] [ASC | DESC] INDEX index_reference ON table_reference (column_reference [,column_reference...])
hailong525 2001-07-27
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create index indexName on tablename(colname)
