FOR XML Clause. The FOR XML clause, will return the results of a SQL query as XML.The FOR XML has four modes which are RAW, AUTO, EXPLICIT or PATH.Introduction to Structured Query Language.Version 4. 7. 1This page is a introductory tutorial of the Structured Query Language also.SQL and is a pioneering effort on the World Wide Web.SQL tutorial available on the Internet.SQL allows users to access data in relational database management systems.An SQL join clause combines columns from one or more tables in a relational database.It creates a set that can be saved as a table or used as it is.Oracle, Sybase, Informix, Microsoft SQL Server, Access, and others.SQL also. allows users to define the data in a database, and manipulate that data.This page will describe how to use SQL, and give examples.The SQL used. in this document is ANSI, or standard SQL, and no SQL features of specific.Nonstandard SQL. It is recommended that you print this page, so that you can easily.Also, you may be interested in joining the new SQL.Club on Yahoo, where you can read or enter messages in a SQL forum.Table of Contents.Basics of the SELECT Statement.Conditional Selection.Relational Operators.Compound Conditions.IN BETWEENUsing LIKEJoins.Keys. Performing a Join.Eliminating Duplicates.Aliases InSubqueries.Aggregate Functions.Views. Creating New Tables.Altering Tables. Adding Data.Deleting Data. Updating Data.Retrieving Records from Multiple Tables.It does no good to put records in a database unless you retrieve them eventually and do something with them.Microsoft Access Update Query examples, SQL Syntax and errors with update queries.Indexes. GROUP BY HAVINGMore Subqueries.EXISTS ALLUNION Outer Joins.Embedded SQLCommon SQL Questions.Nonstandard SQLSyntax Summary.Exercises. Important Links.Basics. of the SELECT Statement.In a relational database, data is stored in tables.An example table.Social Security Number, Name, and Address.Employee. Address.Table. SSNFirst. Name.Last. Name. Address.City. State. 51. 26.Joe. Smith 8. 3 First Street.Howard. Ohio 7. 58.Mary. Scott 8. 42 Vine Ave.Losantiville. Ohio 1.Sam. Jones 3. 3 Elm St.Paris. New York 8.Sarah. Ackerman 4.U. S. 1. 10. Upton.Michigan Now, lets say you want to see the address of each employee.Use the. SELECT statement, like so.SELECT First. Name, Last. Pokemon Yellow Rom Hack Remake Of Roots . Name, Address, City, State.FROM Employee. Address.Table The following is the results of your query of the database.First Name. Last Name.Address. City. State.Joe. Smith. 83 First Street Howard.Ohio. Mary. Scott.Vine Ave. Losantiville.Ohio. Sam. Jones.Elm St. Paris. New York.Sarah. Ackerman. 44.U. S. 1. 10 Upton.Michigan. To explain what you just did, you asked for the all of data in the Employee.Address. Table. and specifically, you asked for the columns called First.Name, Last. Name.Address, City, and State.Note that column names and table names do not.The general form for a SELECT statement, retrieving.SELECT Column. Name, Column.Name,. FROM Table.Name To get all columns of a table without typing all column names, use.SELECT FROM Table.Name Each database management system DBMS and database software has different.SQL commands see the.Conditional Selection.To further discuss the SELECT statement, lets look at a new example.Employee. Statistics.Table. Employee. IDNo.Salary. Benefits.Position. 01. 07.Manager. 10. 56. 50.Manager. 15. 26. 00.Manager. 21. 56. 00.Manager. 24. 45. 00.Staff. 30. 04. 50.Staff. 33. 54. 00.Staff. 40. 03. 20.Entry Level. 44. Entry Level.Relational Operators.There are six Relational Operators in SQL, and after introducing them.Equallt or see manualNot Equal lt Less Than Greater Thanlt Less Than or Equal To Greater Than or Equal To The WHERE clause is used to specify that only certain rows of.WHERE. clause. It is most easily understood by looking at a couple of examples.If you wanted to see the EMPLOYEEIDNOs of those making at or over 5.SELECT EMPLOYEEIDNOFROM EMPLOYEESTATISTICSTABLEWHERE SALARY 5.Notice that the greater than or equal to sign is used, as we wanted.This displays. EMPLOYEEIDNO 0.The WHERE description, SALARY 5.True or False. The same can be.SELECT EMPLOYEEIDNOFROM EMPLOYEESTATISTICSTABLEWHERE POSITION Manager This displays the ID Numbers of all Managers.Generally, with text columns.Note. Position is now an illegal identifier because it is now an unused, but.SQL 9. 2 standard.More Complex Conditions.Compound Conditions Logical Operators.The AND operator joins two or more conditions, and displays a.ALL conditions listed i.For example, to display all staff making over.SELECT EMPLOYEEIDNOFROM EMPLOYEESTATISTICSTABLEWHERE SALARY 4.AND POSITION Staff The OR operator joins two or more conditions, but returns a row.ANY of the conditions listed hold true.To see all those who.SELECT EMPLOYEEIDNOFROM EMPLOYEESTATISTICSTABLEWHERE SALARY lt 4.OR BENEFITS lt 1.AND OR can be combined, for example.SELECT EMPLOYEEIDNOFROM EMPLOYEESTATISTICSTABLEWHERE POSITION Manager AND SALARY 6.OR BENEFITS 1. First, SQL finds the rows where the salary is greater than 6.Manager, then taking this new list of rows.SQL then sees if any of these rows satisfies the previous AND condition.Benefits column is greater than 1.Subsequently. SQL only displays this second new list of rows, keeping in mind that anyone.Benefits over 1. OR operator includes.True. Also note that the AND operation.To generalize this process, SQL performs the AND operations to determine.AND operations hold true remember all of the conditions.OR conditions. and only display those remaining rows where any of the conditions joined.OR operator hold true where a condition or result from an AND is.AND result to use to evaluate the OR.Mathematically, SQL evaluates.AND pairs, and then evaluates.ORs where both operators evaluate left to right.To look at an example, for a given row for which the DBMS is evaluating.SQL statement Where clause to determine whether to include the row.Where clause evaluates to True, the DBMS.True AND False OR True AND True OR False AND False.First simplify the AND pairs.False OR True OR False.Now do the ORs, left to right.True OR False. True.The result is True, and the row passes the query conditions.Be sure. to see the next section on NOTs, and the order of logical operations.I hope that this section has helped you understand ANDs or ORs, as its.To perform ORs before ANDs, like if you wanted to see a list of employees.SELECT EMPLOYEEIDNOFROM EMPLOYEESTATISTICSTABLEWHERE POSITION Manager AND SALARY 5.OR BENEFITS 1. IN BETWEENAn easier method of using compound conditions uses IN or BETWEEN.For example, if you wanted to list all managers and staff.SELECT EMPLOYEEIDNOFROM EMPLOYEESTATISTICSTABLEWHERE POSITION IN Manager, Staff or to list those making greater than or equal to 3.SELECT EMPLOYEEIDNOFROM EMPLOYEESTATISTICSTABLEWHERE SALARY BETWEEN 3.AND 5. 00. 00 To list everyone not in this range, try.SELECT EMPLOYEEIDNOFROM EMPLOYEESTATISTICSTABLEWHERE SALARY NOT BETWEEN 3.AND 5. 00. 00 Similarly, NOT IN lists all rows excluded from the IN list.Additionally, NOTs can be thrown in with ANDs ORs, except that.NOT is a unary operator evaluates one condition, reversing its value.ANDs ORs evaluate two conditions, and that all NOTs.ANDs or ORs. SQL Order of Logical Operations each operates from left to rightNOTANDORUsing LIKELook at the Employee.Statistics. Table, and say you wanted to see all people.S try. SELECT EMPLOYEEIDNOFROM EMPLOYEEADDRESSTABLEWHERE LASTNAME LIKE S The percent sign is used to represent any possible character number.S. To find those people with Last.Names ending in S, use S, or if.S in the middle of the word, try S.The can be. used for any characters in the same position relative to the given characters.NOT LIKE displays rows not fitting the given description.Other possibilities.LIKE, or any of these discussed conditionals, are available, though.DBMS you are using as usual, consult a manual or your.This disclaimer holds for the features of SQL that will be discussed below.This section is just to give you an idea of the possibilities of queries.SQL. Joins. In this section, we will only discuss inner joins, and equijoins.For more information, try the.SQL links at the bottom of the page.Good database design suggests that each table lists data only about.First, take a look at these example tables.Antique. Owners. Owner.IDOwner. Last. Name.Owner. First. Name.Jones. Bill. 02. Smith.Bob. 15. Lawson. Patricia.Akins. Jane. 50. Fowler.Sam. Orders. Owner.IDItem. Desired. 02.Table. 02. Desk. 21.Chair. 15. Mirror.Antiques. Seller.IDBuyer. IDItem. 01.Bed. 02. 15. Table.Chair. 21. 50. Mirror.Desk. 01. 21. Cabinet.Coffee Table. 15.Chair. 01. 15. Jewelry Box.Pottery. 21. 02. Bookcase.Plant Stand. Keys.First, lets discuss the concept of keys.
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