Which comparison operators can you use in a where clause

SQL has several comparison operators. The most simple one is the equal operator. You can compare any data type column using the equal operator. For example:. After executing the SQL the database returns the records where the year column is Where equal is the most used comparison operator, SQL offers many other interesting comparison operators, including:.

For example if you want to obtain the records in the range between and you can use the following query:. The range comparison can be applied to other data types like text strings or date columns.

For example, to obtain the years where harvest started before the first summer storm:. You can also use the inequality operator with numeric, date or text string data type columns to exclude some records.

In this example, you obtain all history production, excluding the apple variety Red Delicious. Get free ground shipping on all U.

Shop now. Now that you are familiar with the concepts of databases and schema diagrams, you are ready to start with hands-on exercises. SQL statements can range from very simple to highly complex; they can be a few words long or a few hundred words long. In this chapter, you begin by writing simple SQL statements, but you will be able to build longer, more complex SQL queries very quickly.

Oracle software runs on many different operating systems and hardware environments. Figure 2. The client sends SQL statements to the server, and the server responds back with the result set. The job of the database server involves listening and managing many clients' requests, because in this configuration there are often multiple client machines involved. For the client computer's programs to communicate with the Oracle database server, the individual client machine is typically configured with the Oracle Net software, or the client may establish an Open Database Connectivity ODBC connection.

Starting with Oracle 8. As with any connection, you obviously need a valid user account and password. The first tier is the client's Web browser, and the middle tier is the Oracle HTTP server Web server that receives requests from the browser and forwards them via Oracle Net to the third tier, the Oracle database server.

The Oracle Web server returns results from the database server back to the Web browser for display. The three tiers may be on one machine but are typically on three different ones. In the midst of all this software lies the SQL language. SQL commands are sent from the client software, also known as the front end, to the server, or back end.

These commands send instructions to the server to tell it what services to provide. The server responds by sending back a result to the client, where it is displayed by the client software.

Note that the user ID and password are not case sensitive. You can access the Oracle server through various front-end tools. The companion Web site to this book lists other alternative query tools. This launches the program and displays the Log On dialog box similar to Figure 2. ORA file. You will learn more about this special file later. The client and the server may now communicate with each other.

To log out, either type exit or QUIT and press enter. Alternatively, you can choose Exit from the File menu or simply use your mouse to close the window. A Log on dialog similar to Figure 2. If you are unsure about your specific port number, try the default port Also notice in Figure 2.

Because the machine is on a local network, you can omit the domain. Instead of the name of the machine, you can enter the IP address. Alternatively, you can use the IP address of Enter the user ID and password in the appropriate boxes. You don't need to supply the Connection Identifier also called Host string to connect to the default database instance.

At the Enter statements text box, also referred to as the input area, you can enter commands. If you want to run a script e. Once the script is loaded into the input area, you can edit the script or simply click the Execute button to execute the script. To logout and return to the Login screen, click on the Logout icon. A command-line interface is available with every Oracle version.

Frequently, you will use this interface in operating systems such as Linux or Unix. Even Windows has a command-line interface and you will see it displayed in Figure 2. Note that depending on the operating system, your editor, as well as the cut and paste commands, may be different. You can also enter sqlplus and you will be prompted for the user name and password or sqlplus student , which will prompt for the password.

Often the database resides on a machine other than your client machine, or you have a choice of accessing different databases. In these cases you need to supply the name of the database in the Host String box of the Log On dialog box see Figure 2.

ORA, which lists the database's IP address or the machine name and database instance name. ORA file is a file containing a list of databases with their respective technical connection information. Your database administrator can help you with the configuration and setup of this file if you have a remote database setup. The entries in your file will obviously vary. Alternatively, you can enter the machine name. When you install Oracle with the default options, you will be asked to supply such an instance name [SID].

A common default name is ORCL. ORA file may contain an entry called default. Note, depending on your individual setup, you may at times need to specify or omit the. While using this site, you agree to have read and accepted our Terms of Service and Privacy Policy. Home SQL. Please re-enable javascript in your browser settings.

Let's use the same suppliers table as the previous example. Let's use the same customers table as the previous example.