SOFTWARE TESTING Documents
SUB QUERIES
A sub query can be defined as a group of nested SELECT statements inside a
SELECT, ...
SOFTWARE TESTING Documents
SubQueries With IN
A subquery introduced with IN returns zero or more values. Consider the
foll...
SOFTWARE TESTING Documents
Sub Queries with EXISTS
The subquery, when used with the EXISTS clause, always returns data in
...
SOFTWARE TESTING Documents
Example:
Example Description
SELECT title_id=title_id, Title=title
FROM title
WHERE prie>ALL(SE...
SOFTWARE TESTING Documents
The select into/bulkcopy database option can be set using the following command:
SELECT title_i...
SOFTWARE TESTING Documents
The region_east table contains the following data:
emp_id emp_name emp_add
- - - - - - - - - - ...
SOFTWARE TESTING Documents
Visit: www.gcreddy.com for QTP Documents
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Sql quaries

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Sql quaries

  1. 1. SOFTWARE TESTING Documents SUB QUERIES A sub query can be defined as a group of nested SELECT statements inside a SELECT, INSERT, UPDATE or DELETE statement. Sub query can also be used inside the WHERE or HAVING clauses of the outer SELECT, INSERT, UPDATE or DELETE statements. SELECT statements containing one or more sub queries are called nested queries. The command syntax is: A subquery must be enclosed within parentheses and cannot use ORDER BY, COMPUTE BY or FOR BROWSE clauses. SQL Server does not implement any restriction on level of nesting while using subqueries, SQL Server imposes restrictions on the number of tables or views used in a subquery or a join. SQL Server evaluates the inner query first and returns the result to the outer query for the final result set. The outer query always depends on the evaluation result of the subquery. Subqueries can be divided into three catefories depending upon the values they return;  Sub queries that operate on lists: this type of query returns single-column- multiple values results and are implemented using the IN clause. The syntax is as follows:  Subqueries that are introduced with an unmodified comparison o-erator: this type of query returns single column-single value results for outer query evaluation and is implemented using unmodified comparison operators(operators without the ANY or ALL keywords) the syntax is as follows:  Subqueries that check for the existence of data: this type of query checks for the existence of records in a table that are used in the inner query, and returns either a TRUE or a FALSE VALUE based on the existence of data. This is implemented using the EXISTS keyword. The syntax is as follows: Visit: www.gcreddy.com for QTP Documents 1 (SELECT [ALL|DISTINCT] suquery_select_list [FROM {table_nmae | view_name} [[,table_name2|view_name2}] [..,{table_name16|view_name16{]] [WHERE clause] GROUP BY clause] [HAVING clause]) WHERE expression [NOT] IN (subquery) WHERE expression comparison_operator [ANY|ALL] (subquery)
  2. 2. SOFTWARE TESTING Documents SubQueries With IN A subquery introduced with IN returns zero or more values. Consider the following example where all author ID’S, from the TITLEAUTHOR table, are displayed whose books are sold: SQL Server returns a list of all title IDs to the main query then lists all the authors, whose books are sold, in the result set. Consider the following example where the server returns a list of publisher IDs to the main query, and then determines whether each publisher’s pub_id is in that list: The inner query is evaluated first and then the result set is sent to the outer query. Consider another subquery with the IN clause: The inner query is evaluated first and then the result set is sent to the outer query. The NOT IN clause is used in the same way as the IN clause. Consider the following example. Visit: www.gcreddy.com for QTP Documents 2 WHERE [NOT] EXISTS (subquery) SELECT au_id FROM titleauthor WHERE title_id IN (SELECT title_id FROM sales) SELECT publisher=pub_name FROM publishers WHERE pub_id IN ( SELECT pub_id FROM titles WHERE type=’business’) SELECT type=type, Average=AVG(ytd_sales) FROM titles WHERE type IN (SELECT type FROM titles WHERE title=” the busy executive’s database guide” or title=’Is Anger the Enemy?’) GROUUP BY type SELECT pub_id, pub_name FROM publishers WHERE pub_id NOT IN (SELECT pub_id FROM titles WHERE type=’mod_cook’)
  3. 3. SOFTWARE TESTING Documents Sub Queries with EXISTS The subquery, when used with the EXISTS clause, always returns data in terms of TRUE OR FALSE and passes the status to the outer query to produce the results set. The subquery returns a TRUE value if the result set contains any rows. The query introduced with the EXISTS keyword differs from other queries. The EXISTS keyword is not preceded by any column name, constant or there expression and it contains an asterisk (*) in the SELECT list. Aggregate functions can also be used in subqueries. Consider the following example which displays the titles of all those books for which the advance is more than the average advance of business related books. Subquery Restrictions: The restrictions imposed are:  The column list of the select statement of a subquery introduced with the comparison operator can include only one column.  The column used in the WHERE clause of the outer query should be compatible with the column used in the select list of the inner query.  The DISTINCT keyword cannot be used with the subqueries that include the GROUP BY clause.  The ORDER BY clause, GROUP BY clause and INTO keyword cannot be used in a subquery, because a subquery cannot manipulate its result internally.  Do not specify more than one column name in the subquery introduced with the EXISTS keyword.  A view created with a subquery cannot be updated. Nested Sub Queries: A sub query can contain one or more subqueries. There is no restriction in the number of subqueries that you can include with SELECT, INSERRT, UPDATE or DELETE statements. Visit: www.gcreddy.com for QTP Documents 3 1. SELECT pub_name FROM publishers WHERE EXISTS (SELECT * FROM titles WHERE type=’business’) 2. SELECT pub_name FROM publishers WHERE EXISTS (SELECT * FROM publishers WHERE City=’Paris’) SELECT Title=title FROM titles WHERE advance>(SELECT AVG (advance) from titles WHERE type=’business’)
  4. 4. SOFTWARE TESTING Documents Example: Example Description SELECT title_id=title_id, Title=title FROM title WHERE prie>ALL(SELECT price FROM titles WHERE pub_id=’0736’) Lists all the titles along with their IDs from the titles table where price is greater than the maximum price of books published by the publisher with publisher ID 0736. SELECT title_ID = title_id, Title = title FROM titles WHERE price >ANY (SELECT price FROM titles WHERE pub_id = `0736`) Lists all the titles along with their titles IDs from the titles table where price is greater than the minimum price of books published by the publisher with publisher ID 0736. SELECT publisher_ID = pub_id, Name = pub_name FROM publishers WHERE city = ANY (SELECT city FROM authors) Lists all the publishers where city is sane as of any author. SELECT INTO Statement A SELECT statement with an INTO clause is used to store the result set in a new table without a data definition process. The SELECT INTO statement creates a new table, if the table already exists then the operation fails. The syntax of the SELECT INTO statement is: The SELECT INTO clause creates a permanent table if the select into/bulk copy database option is set. If the select into/bulkcopy database option is not set, then only local temporary tables (prefixed by #), and global temporary tables (prefixed by ##) can be created. Visit: www.gcreddy.com for QTP Documents 4 1. SELECT ‘Author Name’=SUBSTRING (au_fname, 1,1)+’.’+au_lastname FROM authors WHERE au_id IN(SELECT au_id FROM titleauthor WHERE title=’Net Etiquette’)) 2. SELECT ‘Author ID’=au_id, Name=SUBSTRING (au_fnmae, 1,1) + ‘.’+au_lname FROM authors WHERE au_id IN (SELECT au_id FROM titleauthor WHERE type=’business’)) SELECT columns_list INTO new_table_name FROM table_names WHERE conditions
  5. 5. SOFTWARE TESTING Documents The select into/bulkcopy database option can be set using the following command: SELECT title_id, title INTO newtitles From titles WHERE price >$15 Column names in the new table can be changed while specifying the columns in the SELECT statement. Consider the following example with the new column names: UNION SQL Server provides a unique operator known as the UNION operator that is used to combine the result set or more queries. The syntax is: By default, the result set of the UNION operator removes the duplicate rows from the queries combined, until an ALL clause is specified with the UNION operator. The queries combined with the UNION operator must contain an equal number of columns or expressions, and they must be compatible with each other There are two tables: region_east and region_west. The region_east table contains the employee id, name and address of the employees of the eastern region. The region_west table contains the employee id, name and the address of the employees of the western region. Visit: www.gcreddy.com for QTP Documents 5 sp_dboption ‘pubs’, ‘select into / bulkcopy ‘, true SELECT Title _ID = title _id, Title_Name =title INTO new titles 1 FROM titles WHERE advance >$7000 SELECT column_list [INTO new_table_name] [FROM clause] [WHERE clause] [GROUP BY clause] [HAVING clause]….] [ORDER BY clause] [COMPUTE clause]
  6. 6. SOFTWARE TESTING Documents The region_east table contains the following data: emp_id emp_name emp_add - - - - - - - - - - - - - - - - - - - - - - - - -- -- - - - - - - - - - - - - - - - - - E001 George 323, Park Avenue Street E002 Jack 475, Barbara Lines E003 Nancy 68, Bank Street The region_west table contains the following data: Emp_id emp_name emp_add - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - -- - - - - - - - - W001 Maria 45, Canara Street W002 James 12, Blue Lines W003 Jill 98, Civil Lines The following statement displays employee ids and names of the both the regions: east and the west. SELECT emp_id emp_name FROM region_east Union SELECT emp_id, emp_name FROM region_west SELECT ‘Employee ID’ =emp_id, ‘Employee Name’=emp_name FROM region_east Union SELECT emp_, emp_name FROM region_west Rules Regarding the use of the UNION Operator The restrictions imposed by SQL Server on the use of the UNION operator are listed below: • Corresponding columns in the individual queries of a UNION statement must occur in the same order, because UNION compares the columns in the order specified in the individual queries. • The columns or expressions used in one query must be equal in number, and should be compatible with the columns or expressions of other queries. • The first query in the UNION statement can only contain the INTO clause to store the final result set. The INTO clause cannot be used with any query other than the first query while implementing the UNION operator. • The ORDER BY and COMPUTE BY clauses cannot be used in an individual query. These clauses can be used only at the end of the last query to summarize and order the final result set. • The GROUP BY and HAVING clauses can only be used with individual queries and cannot be used for the final result to be set. • The UNION operator can also be used with the INSERT statement. Visit: www.gcreddy.com for QTP Documents 6
  7. 7. SOFTWARE TESTING Documents Visit: www.gcreddy.com for QTP Documents 7

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