Write a SQL query to create a table with three columns: id, name, and age. Add a primary key constraint on the id column. Write a SQL query to create a table with four columns: product_id, product_name, price, and quantity. Ensure that the price column cannot have negative values...
可使用 INSERT INTO 语句向空表写入数据。 SQL 约束 约束用于限制加入表的数据的类型。 可以在创建表时规定约束(通过 CREATE TABLE 语句),或者在表创建之后也可以(通过 ALTER TABLE 语句)。 我们将主要探讨以下几种约束: NOT NULL UNIQUE PRIMARY KEY FOREIGN KEY CHECK DEFAULT SQL NOT NULL 约束 NOT NULL 约束...
Here, the SQL command checks if a table namedCompaniesexists, and if not, it creates a table with specified columns. Create Table Using Another Existing Table In SQL, we can create a new table by duplicating an existing table's structure. Let's look at an example. -- create a backup t...
適用於:Microsoft Fabric 中的 SQL ServerAzure SQL 資料庫 Azure SQL 受控執行個體SQL 資料庫 在資料庫中建立新的數據表。 注意 如需在 Microsoft Fabric 中倉儲的參考,請流覽 CREATE TABLE (網狀架構數據倉儲)。 如需 Azure Synapse Analytics 和分析平台系統 (PDW) 的參考,請造訪 CREATE TABLE (Azure ...
sql SELECTpatient_id, name, age, gender, address, disease, doctor_idFROMfemale_patient; SQL CREATE STATEMENT | NOT NULL, PRIMARY KEY constraints Use SQL Create a statement to create a patient table which having patient_id as a primary key column with auto-increment, patient name, and disease...
] referenced_table_name [ ( ref_column ) ] | CHECK ( logical_expression ) } <table_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED ( column_name [ ASC | DESC ] [ ,... n ]) | NONCLUSTERED HASH ( column_name [ ,... n ] ) WITH ...
使用SHOW CREATE TABLE命令 查看information_schema.TABLE_CONSTRAINTS视图 查看information_schema.CHECK_CONSTRAINTS视图 constraint_name约束名称,最多包含 64 个字符。 约束名称的开头结尾中间都允许有空格,但需要用"`"标识名称的开头和结尾。 约束名称可以包含特殊字符"$"。
When creating a managed U-SQL table with a schema, a table schema has to be provided that contains at least one table column definition. Syntax Create_Managed_Table_With_Schema_Statement := 'CREATE' 'TABLE' ['IF' 'NOT' 'EXISTS']IdentifierTable_With_Schema. ...
IF v_partition_keyISNOTNULLTHENv_table_ddl :=v_table_ddl||' PARTITION BY '||v_partition_key;ENDIF;ENDIF; v_table_ddl :=v_table_ddl||';'||E'\n';-- suffix create statement with all of the indexes on the tableFORv_index_recordINSELECTregexp_replace(indexdef,' "?'||schemaname|...
Constraints 约束 Drop Table Truncate Table Create Table 创建表 CREATE [TEMPORARY] [EXTERNAL] TABLE [IF NOT EXISTS] [db_name.]table_name -- (Note: TEMPORARY available in Hive 0.14.0 and later) [(col_name data_type [COMMENT col_comment], ... [constraint_specification])] ...