GlobAl EDITION. Database Concepts SEVENTH EDITION. David M. Kroenke David J. Auer

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1 GlobAl EDITION Database Concepts SEVENTH EDITION David M. Kroenke David J. Auer

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3 Chapter 3 Structured Query Language 157 the comment. We will use similar comments to label the SQL statements in this chapter as an easy way to reference a specific SQL statement in the text. The data shown in Figure 3-2(c) will be put in the PROJECT table. Because ProjectID is a surrogate key specified as IDENTITY (1000, 100) in SQL Server the same type of INSERT statement can be used when data are supplied for all other columns. For example, to insert the data for the 2014 Q3 Product Plan, the following INSERT can be used: /* *** SQL-INSERT-CH03-02 *** */ INSERT INTO PROJECT VALUES('2014 Q3 Product Plan', 'Marketing', , '10-MAY-14', '15-JUN-14'); Note that numbers such as Integer and Numeric values are not enclosed in single quotes, but Char, VarChar, and DateTime values are. BTW SQL is very fussy about single quotes. It wants the plain, nondirectional quotes found in basic text editors. The fancy directional quotes produced by many word processors will produce errors. For example, the data value '2014 Q3 Product Plan' is correctly stated, but 2014 Q3 Product Plan is not. Do you see the difference? If data for some columns are missing, then the names of the columns for which data are provided must be listed. For example, consider the 2014 Q4 Portfolio Analysis project, which does not have an EndDate value. The correct INSERT statement for this data is: /* *** SQL-INSERT-CH03-03 *** */ INSERT INTO PROJECT (ProjectName, Department, MaxHours, StartDate) VALUES('2014 Q4 Portfolio Analysis', 'Finance', , '05-OCT-14'); A NULL value will be inserted for EndDate. Let s consider three points regarding the second version of the INSERT command. First, the order of the column names must match the order of the values. In the preceding example, the order of the column names is Name, Department, MaxHours, StartDate, so the order of the values must also be Name, Department, MaxHours, StartDate. Second, although the order of the data must match the order of the column names, the order of the column names does not have to match the order of the columns in the table. For example, the following INSERT, where Department is placed at the beginning of the column list, would also work: /* *** SQL-INSERT-CH03-04 *** */ INSERT INTO PROJECT (Department, ProjectName, MaxHours, StartDate) VALUES('Finance', '2014 Q4 Portfolio Analysis', , '05-OCT-14'); Finally, for the INSERT to work, values for all NOT NULL columns must be provided. You can omit EndDate only because this column is defined as NULL.

4 158 Part 1 Database Fundamentals Figure 3-12 shows the SQL INSERT statements needed to populate the WPC database tables created by the SQL CREATE TABLE statements in Figure 3-7. Note that the order in which the tables are populated does matter because of the foreign key referential integrity constraints. FIGURE 3-12 SQL INSERT Statements

5 Chapter 3 Structured Query Language 159 FIGURE 3-12 Continued BTW Oracle Database and MySQL handle surrogate keys in their own unique ways. Oracle Database uses sequences (see Appendix B and the Oracle Database Express Edition 11g Release 2 documentation), and MySQL treats the AUTO_INCREMENT value as a missing value so that you have to list all the other column names (see Appendix C and the MySQL 5.6 Community Server documentation). SQL FOR DATA MANIPULATION (DML) SINGLE TABLE QUERIES After the tables have been defined and populated, you can use SQL DML to query data in many ways. You can also use it to change and delete data, but the SQL statements for these activities will be easier to learn if we begin with the query statements. In the following discussion, assume that the sample data shown in Figure 3-2 have been entered into the database.

160 Part 1 Database Fundamentals The SQL SELECT/FROM/WHERE Framework This section introduces the fundamental statement framework for SQL query statements.

6 160 Part 1 Database Fundamentals The SQL SELECT/FROM/WHERE Framework This section introduces the fundamental statement framework for SQL query statements. After we discuss this basic structure, you will learn how to submit SQL statements to Microsoft Access, SQL Server, Oracle Database, and MySQL. If you choose, you can then follow along with the text and process additional SQL statements as they are explained in the rest of this chapter. The basic form of SQL queries uses the SQL SELECT/FROM/ WHERE framework. In this framework: The SQL SELECT clause specifies which columns are to be listed in the query results. The SQL FROM clause specifies which tables are to be used in the query. The SQL WHERE clause specifies which rows are to be listed in the query results. We will use and expand this framework as we work through examples in the following sections. All the examples use the data in Figure 3-2 as the basis for the results of the queries. Reading Specified Columns from a Single Table The following SQL statement queries (reads) three of the six columns of the PROJECT table: /* *** SQL-QUERY-CH03-01 *** */ SELECT ProjectName, Department, MaxHours FROM PROJECT; Notice that the names of the columns to be queried follow the keyword SELECT, and the name of the relation to use follows the keyword FROM. The result of this statement is: To show you how the results look in actual DBMS management tools, Figure 3-13 shows the query as executed in Microsoft SQL Server 2014 using Microsoft SQL Server Management Studio, Figure 3-14 shows the query as executed in Oracle Database Express Edition 11g Release 2 using Oracle SQL Developer, and Figure 3-15 shows the query as executed in the MySQL 5.6 using MySQL Workbench. The result of an SQL SELECT statement is a relation. This is always true for SELECT statements. They start with one or more relations, manipulate them in some way, and then produce a relation. Even if the result of the manipulation is a single number, that number is considered to be a relation with one row and one column. The order of the column names after the keyword SELECT determines the order of the columns in the resulting table. Thus, if you change the order of columns in the previous SELECT statement to: /* *** SQL-QUERY-CH03-02 *** */ SELECT ProjectName, MaxHours, Department FROM PROJECT;

FIGURE 3-14 SQL Query Results in the Oracle SQL Developer The WPC tabbed SQL Worksheet window The Run

7 Chapter 3 Structured Query Language 161 FIGURE 3-13 SQL Query Results in the Microsoft SQL Server Management Studio The New Query button The Execute button The SQL statement in the tabbed query window The query results FIGURE 3-14 SQL Query Results in the Oracle SQL Developer The WPC tabbed SQL Worksheet window The Run Statement button The SQL statement in the tabbed SQL Worksheet window The query results in the tabbed Query Result window

Database Concepts. Online Appendix A Getting Started with Microsoft SQL Server 2014 Express. 7th Edition. David M. Kroenke David J.

Database Concepts. Online Appendix A Getting Started with Microsoft SQL Server 2014 Express. 7th Edition. David M. Kroenke David J. Database Concepts 7th Edition David M. Kroenke David J. Auer Online Appendix A Getting Started with Microsoft SQL Server 2014 Express All rights reserved. No part of this publication may be reproduced,