表是用來儲存資料和運算元據的邏輯結構,用來組織和儲存資料,關聯式資料庫中的所有資料都表現為表的形式,資料表由行和列組成。SQL Server中的資料表分為臨時表和永久表,臨時表儲存在tempdb系統資料庫中,當不再使用或退出SQL Server時,臨時表會自動刪除;永久表一旦建立之後,除非使用者刪除,否則將一直存在資料庫檔案中。
建立資料表的兩種方法:(1) 通過物件資源管理器建立;(2) 通過Transact-SQL語句進行建立。
1 Transact-SQL建立表
1.1 語法
CREATE TABLE [ database_name . [ schema_name ] . | schema_name . ] table_name ( { <column_definition> | <computed_column_definition> | <column_set_definition> } [ <table_constraint> ] [ ,...n ] ) [ ON { partition_scheme_name ( partition_column_name ) | filegroup | "default" } ] [ { TEXTIMAGE_ON { filegroup | "default" } ] [ FILESTREAM_ON { partition_scheme_name | filegroup | "default" } ] [ WITH ( <table_option> [ ,...n ] ) ] [ ; ] <column_definition> ::= column_name <data_type> [ FILESTREAM ] [ COLLATE collation_name ] [ NULL | NOT NULL ] [ [ CONSTRAINT constraint_name ] DEFAULT constant_expression ] | [ IDENTITY [ ( seed ,increment ) ] [ NOT FOR REPLICATION ] ] [ ROWGUIDCOL ] [ <column_constraint> [ ...n ] ] [ SPARSE ] <data type> ::= [ type_schema_name . ] type_name [ ( precision [ , scale ] | max | [ { CONTENT | DOCUMENT } ] xml_schema_collection ) ] <column_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] [ WITH FILLFACTOR = fillfactor | WITH ( < index_option > [ , ...n ] ) ] [ ON { partition_scheme_name ( partition_column_name ) | filegroup | "default" } ] | [ FOREIGN KEY ] REFERENCES [ schema_name . ] referenced_table_name [ ( ref_column ) ] [ ON DELETE { NO ACTION | CASCADE | SET NULL | SET DEFAULT } ] [ ON UPDATE { NO ACTION | CASCADE | SET NULL | SET DEFAULT } ] [ NOT FOR REPLICATION ] | CHECK [ NOT FOR REPLICATION ] ( logical_expression ) } <computed_column_definition> ::= column_name AS computed_column_expression [ PERSISTED [ NOT NULL ] ] [ [ CONSTRAINT constraint_name ] { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] [ WITH FILLFACTOR = fillfactor | WITH ( <index_option> [ , ...n ] ) ] | [ FOREIGN KEY ] REFERENCES referenced_table_name [ ( ref_column ) ] [ ON DELETE { NO ACTION | CASCADE } ] [ ON UPDATE { NO ACTION } ] [ NOT FOR REPLICATION ] | CHECK [ NOT FOR REPLICATION ] ( logical_expression ) [ ON { partition_scheme_name ( partition_column_name ) | filegroup | "default" } ] ] <column_set_definition> ::= column_set_name XML COLUMN_SET FOR ALL_SPARSE_COLUMNS < table_constraint > ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] (column [ ASC | DESC ] [ ,...n ] ) [ WITH FILLFACTOR = fillfactor |WITH ( <index_option> [ , ...n ] ) ] [ ON { partition_scheme_name (partition_column_name) | filegroup | "default" } ] | FOREIGN KEY ( column [ ,...n ] ) REFERENCES referenced_table_name [ ( ref_column [ ,...n ] ) ] [ ON DELETE { NO ACTION | CASCADE | SET NULL | SET DEFAULT } ] [ ON UPDATE { NO ACTION | CASCADE | SET NULL | SET DEFAULT } ] [ NOT FOR REPLICATION ] | CHECK [ NOT FOR REPLICATION ] ( logical_expression ) } <table_option> ::= { DATA_COMPRESSION = { NONE | ROW | PAGE } [ ON PARTITIONS ( { <partition_number_expression> | <range> } [ , ...n ] ) ] } <index_option> ::= { PAD_INDEX = { ON | OFF } | FILLFACTOR = fillfactor | IGNORE_DUP_KEY = { ON | OFF } | STATISTICS_NORECOMPUTE = { ON | OFF } | ALLOW_ROW_LOCKS = { ON | OFF} | ALLOW_PAGE_LOCKS ={ ON | OFF} | DATA_COMPRESSION = { NONE | ROW | PAGE } [ ON PARTITIONS ( { <partition_number_expression> | <range> } [ , ...n ] ) ] } <range> ::= <partition_number_expression> TO <partition_number_expression>
2 Transact-SQL修改表
2.1 語法
ALTER TABLE [ database_name . [ schema_name ] . | schema_name . ] table_name { ALTER COLUMN column_name { [ type_schema_name. ] type_name [ ( { precision [ , scale ] | max | xml_schema_collection } ) ] [ COLLATE collation_name ] [ NULL | NOT NULL ] [ SPARSE ] | {ADD | DROP } { ROWGUIDCOL | PERSISTED | NOT FOR REPLICATION | SPARSE } } | [ WITH { CHECK | NOCHECK } ] | ADD { <column_definition> | <computed_column_definition> | <table_constraint> | <column_set_definition> } [ ,...n ] | DROP { [ CONSTRAINT ] { constraint_name [ WITH ( <drop_clustered_constraint_option> [ ,...n ] ) ] } [ ,...n ] | COLUMN { column_name } [ ,...n ] } [ ,...n ] | [ WITH { CHECK | NOCHECK } ] { CHECK | NOCHECK } CONSTRAINT { ALL | constraint_name [ ,...n ] } | { ENABLE | DISABLE } TRIGGER { ALL | trigger_name [ ,...n ] } | { ENABLE | DISABLE } CHANGE_TRACKING [ WITH ( TRACK_COLUMNS_UPDATED = { ON | OFF } ) ] | SWITCH [ PARTITION source_partition_number_expression ] TO target_table [ PARTITION target_partition_number_expression ] [ WITH ( <low_lock_priority_wait> ) ] | SET ( FILESTREAM_ON = { partition_scheme_name | filegroup | "default" | "NULL" } ) | REBUILD [ [PARTITION = ALL] [ WITH ( <rebuild_option> [ ,...n ] ) ] | [ PARTITION = partition_number [ WITH ( <single_partition_rebuild_option> [ ,...n ] ) ] ] ] | <table_option> | <filetable_option> } [ ; ]
2.2 示例
修改表新增新列
ALTER TABLE [dbo].[Product] ADD [UnitPrice] DECIMAL(18,2) NULL
ALTER TABLE [dbo].[Product] ADD [UnitsInStock] INT NULL, [UnitsOnSale] INT NULL
修改列
ALTER TABLE [dbo].[Product] ALTER COLUMN [ProductName] VARCHAR(100) NOT NULL
刪除列
ALTER TABLE [dbo].[Product] DROP COLUMN [UnitPrice]
3 Transact-SQL刪除表
3.1 語法
DROP TABLE [ database_name . [ schema_name ] . | schema_name . ] table_name [ ,...n ] [ ; ]
4 表操作示例
檢視資料庫中全部的表
USE [Portal] GO SELECT * FROM INFORMATION_SCHEMA.TABLES GO
INFORMATION_SCHEMA是一個特定的訪問路徑,用於顯示系統資料庫及其內容的相關後設資料。如INFORMATION_SCHEMA.VIEWS、INFORMATION_SCHEMA.SCHEMATA。
檢視錶的屬性
儲存過程sp_help的功能是檢視任意資料庫物件、使用者自定義資料型別或SQL Server資料型別的資訊。
執行儲存過程sp_help的語法結構:
EXEC sp_help <name>
檢視Product表的屬性:
EXEC sp_help Product