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barcode for .NET The Select Statement in Java Compose UPC-A in Java The Select Statement

The Select Statement using barcode printing for none control to generate, create none image in none applications.pdf-417 creating asp.net In SQL, the se none for none lect statement is used to get information from a table. Much of this book is concerned with the select statement. This chapter explains its four basic clauses and the options available for three of these clauses.

. ISO Specification The goal: Get a few columns and rows from a table Our goal is to none for none get the data we want from a table. The table may be large and contain a lot of data. We only want a small part of it and we do not want to change the data in any way.

The select statement allows us to retrieve a few columns and a few rows of data from the table. Let s put some numbers on this. The particular numbers are not important, but they draw the picture more clearly.

Suppose that printing all the data in the table would take 1,000 pages, and suppose we want only two pages of data from it. The select statement allows us to get just the two pages of data we want. It is as if we want to read an article on redwood trees from an encyclopedia.

We only want to see that one article. We do not want to read the entire encyclopedia from beginning to end. The select statement allows us to find the particular article we want to read.

The following diagram shows a large table of data. A small amount of that data is being retrieved into the result of the select statement. In this diagram, the data we want is scattered throughout the table in various columns and rows.

It is collected together by the select statement.. A B C D E A C E Beginning table. Result table. CHAPTER 2 GETTING INFORMATION FROM A TABLE Handling small tables of data If a table of none for none data is small, there might not be much reason to write a select statement. For instance, if we can print the entire table on two pages, then why not print it completely and let people work to find the information they want In many situations, this approach makes the most sense. In this book, we use small tables as learning tools.

With tables this size, there is not much reason to use select statements. However, these tables are being used as examples to show how the select statement works when it is used with larger tables..

Overview of the select statement The select sta none none tement is used to get some of the data from a table. It has six clauses:. select from where group by having order by Which columns none none of data to get Which table has the data Which rows of data to get (Described in chapter 12) (Described in chapter 12) Which columns are used to sort the result. They must be w ritten in this order. Group by and having are used in summarizing data, and we examine them later. This chapter discusses the options available for the select, where, and order by clauses.

For now, the from clause will always list only one table. A select statement is often called a query. These two terms are used interchangeably.

The term select statement emphasizes the syntax of the SQL command. The term query emphasizes the purpose of the command..

THE SELECT STATEMENT Task Show an exampl none for none e of a select statement that uses all of the clauses just listed. Show the employee_id, last_name, and credit_limit columns from the l_employees table of the Lunches database. Show only the employees who have a credit limit greater than $20.

00. Sort the rows of the result by the last name of the employee..

Oracle & Access SQL select employe none none e_id, last_name, credit_limit from l_employees where credit_limit > 20.00 order by last_name; . Beginning tabl e (l_employees table). EMPLOYEE ID -- none for none -----201 202 203 204 205 206 207 208 209 210 FIRST_NAME ---------SUSAN JIM MARTHA ELLEN HENRY CAROL DAN FRED PAULA NANCY LAST_NAME --------BROWN KERN WOODS OWENS PERKINS ROSE SMITH CAMPBELL JACOBS HOFFMAN DEPT CODE ---EXE SAL SHP SAL SAL ACT SHP SHP MKT SAL CREDIT PHONE HIRE_DATE LIMIT NUMBER ------------ ------- -----01-JUN-1998 $30.00 3484 16-AUG-1999 $25.00 8722 02-FEB-2009 $25.

00 7591 01-JUL-2008 $15.00 6830 01-MAR-2006 $25.00 5286 (null) (null) (null) 01-DEC-2008 $25.

00 2259 01-APR-2008 $25.00 1752 17-MAR-1999 $15.00 3357 16-FEB-2007 $25.

00 2974 MANAGER ID ------(null) 201 201 202 202 (null) 203 203 201 203.
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