FOREIGN KEY: The foreign key is a column that creates a link between two tables. The foreign key of any table refers to the Primary Key of another table. A table can have one or more foreign keys. A foreign key constraint prevents the UPDATE and DELETE statement that breaks the link bet...
("Northwind.mdb")' Create a table with three fields and a unique' index made up of all three fields.dbs.Execute"CREATE TABLE MyTable "_ &"(FirstName CHAR, LastName CHAR, "_ &"DateOfBirth DATETIME, "_ &"CONSTRAINT MyTableConstraint UNIQUE "_ &"(FirstName, LastName, DateOfBirth));...
("Northwind.mdb")' Create a table with three fields and a unique' index made up of all three fields.dbs.Execute"CREATE TABLE MyTable "_ &"(FirstName CHAR, LastName CHAR, "_ &"DateOfBirth DATETIME, "_ &"CONSTRAINT MyTableConstraint UNIQUE "_ &"(FirstName, Last...
<column_set_definition> ::= column_set_name XML COLUMN_SET FOR ALL_SPARSE_COLUMNS <table_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] ( column_name [ ASC | DESC ] [ ,... n ] ) [ WITH FILLFA...
columnis the name of a column in the table datatypeis the type of data that the column can hold (e.g., integer, varchar, date) Example: SQL CREATE TABLE -- create a table Students with different columnsCREATETABLEStudents(idint,namevarchar(50), ...
Column-options NOT NULLLob-options7SCOPEtyped-table-nametyped-view-name8CONSTRAINTconstraint-namePRIMARY KEYUNIQUEReferences-clauseCHECK(check-condition)constraint-attributes9Default-clausegenerated-clauseINLINE LENGTHinteger10COMPRESS SYSTEM DEFAULTCOLUMNSECURED WITHsecurity-label-nameNOT HIDDENIMPLICITLY HIDDEN Lob...
要创建已创建的临时表,请使用 CREATE GLOBAL TEMPORARY TABLE 语句。 要声明已声明的临时表,请使用 DECLARE GLOBAL TEMPORARY TABLE 语句。 调用 此语句可以嵌入在应用程序中,也可通过动态 SQL 语句来发出。 它是一个可执行语句,仅当 DYNAMICRULES 运行行为对于程序包有效时才能动态编译 (SQLSTATE 42509)。
You can also create an object type and then use it in a column when creating a relational table. Tables are created with no data unless a subquery is specified. You can add rows to a table with theINSERTstatement. After creating a table, you can define additional columns, partitions, and...
CREATE [TEMPORARY] [EXTERNAL] TABLE [IF NOT EXISTS] [db_name.]table_name LIKE existing_table_or_view_name [LOCATION hdfs_path]; data_type : primitive_type | array_type | map_type | struct_type | union_type -- (Note: Available in Hive 0.7.0 and later) ...
CREATE UNIQUE INDEX index1 ON schema1.table1 (column1 DESC, column2 ASC, column3 DESC); 主要方案:从SQL Server 2016 (13.x) 和 SQL 数据库开始,可针对列存储索引使用非聚集索引来提高数据仓库查询性能。 有关详细信息,请参阅列存储索引 - 数据仓库。有...