SQL > Data Definition Language (DDL) > Create Table Statement In a relational database, data is stored in tables. Given that there is no way for the database vendor to know ahead of time what your data storage needs are, you will for sure need to create tables that fit your needs ...
Subqueries can return one or multiple records and can use the aliases defined in the outer query. The following example shows a query that uses a subquery to count allBooks written by anAuthorand returns only theAuthors who’ve written more than 1 Book. SELECTaFROMAuthor aWHERE(SELECTcount(b...
and they are described in detail in the Data Warehousing Guide. The most important of these other methods is to use a SQL subquery as the argument for anINoperator. When usingFORconstructs with subqueries, it is essential to examine the total number of rules that theFORconstruct may generate...
SQL Server: CREATE TABLE Customer (SID integer PRIMARY KEY, Last_Name nvarchar(30), First_Name nvarchar(30)); In the examples above, SID column is specified as the primary key. Below is an example of specifying the primary key on a single column usingALTER TABLE. The same SQL statement ...
C. The main query executes with all the values returned by the subquery. D. The main query fails because the multiple-row subquery cannot be used with the comparison operator. E. You cannot define a multiple-row subquery in the WHERE clause of a SQL query.相关...
Subqueries can return one or multiple records and can use the aliases defined in the outer query. The following example shows a query that uses a subquery to count allBooks written by anAuthorand returns only theAuthors who’ve written more than 1 Book. ...