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Anita Philipp – Spring 2010

SELECT WHERE INSERT DELETE. Structured Query Language MySQL~PHP. Anita Philipp – Spring 2010. Objectives. Study the basics of databases and MySQL Work with MySQL databases Define database tables Modify user privileges Work with database records Work with phpMyAdmin.

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Anita Philipp – Spring 2010

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  1. SELECT WHERE INSERT DELETE Structured Query Language MySQL~PHP Anita Philipp – Spring 2010

  2. Objectives • Study the basics of databases and MySQL • Work with MySQL databases • Define database tables • Modify user privileges • Work with database records • Work with phpMyAdmin

  3. Introduction to Databases • Database • Ordered collection of information • Can quickly access information • Each row in a database table is called a record • Record • Single complete set of related information - Row • Fields • Columns in a database table • Individual categories of information stored in a record

  4. Introduction to Databases • Flat-File Database • Stores information in a single table • Relational Database • Stores information across multiple related tables

  5. Understanding Relational Databases • Primary Table • main table in a relationship that is referenced by another table • Related Table (or “child table”) • references a primary table in a relational database • Primary Key • field that contains a unique identifier for each record in a primary table • Foreign Key • field in a related table that refers to primary key in primary table • link records across multiple tables

  6. One-to-One Relationships • Related table - one record for each record in the primary table • Breaks information into multiple, logical sets • Could be placed within a single table • Make one table confidential and accessible only by certain individuals

  7. One-to-Many Relationship • One-to-Many Relationship • one record in a primary table has many related records in a related table • Normalization • multiple related tables to reduce redundant and duplicate information

  8. One-to-Many Relationship Figure 7-3 Table with Redundant Information Figure 7-4 One-to-Many Relationship

  9. Many-to-Many Relationship Junction Table • Sometimes called “cross-reference” table • Creates a one-to-many relationship for each of the two tables in a many-to-many relationship • Compound key: employee_id and language_id • Number of years each programmer has worked with each language Figure 7-5 Many-to-Many Relationship

  10. Working with Database Management Systems • DataBase Management System (DBMS) • Application or collection of applications used to access and manage a database • Schema • Structure of a database including its tables, fields, and relationships • Flat-File Database Management System • Stores data in a flat-file format (text file, one record per line) • Sometimes refers to a one table database • Relational DataBase Management System (RDBMS) • Stores data in a relational format

  11. Working with DBMS • Query • Structured set of instructions and criteria for retrieving, adding, modifying, and deleting • Structured Query Language (SQL) • Data manipulation language • Open DataBase Connectivity (ODBC) • Allows ODBC-compliant applications to access any data source for which there is an ODBC driver

  12. SQL-Structured Query Language SQL • Most widely used language for defining and manipulating relational databases 1. Create new databases 2. Add/modify tables 3. Search for Data 4. Build new tables from existing ones 5. Remove tables and data

  13. SQL Language SQL • Data Definition Language (DDL) …defining databases, tables, indexes • Data Manipulation Language (DML) …searching, retrieving, modifying, inserting, deleting, updating table data

  14. Data Manipulation Language SQL • Parameter Declarations • …optional parameters that can be passed to the query • Manipulative Statement • …Indicates the type of action to be taken • (INSERT, DELETE, SELECT, or UPDATE) • Options • …Conditions for selecting record, grouping, ordering, • totaling of records • (FROM, WHERE, GROUP BY, HAVING, ORDER BY • Aggregate Functions • …process multiple record maybe (subset of entire table) • (AVG, COUNT, SUM, MAX, MIN)

  15. SQL Two Types of Statements Selection Query Retrieves one or more rows Action Query Actions such as update, delete Does not retrieve any rows

  16. Selection Queries

  17. Selection Query - Format

  18. Retrieving Data – SELECT Statement • SELECT Field FROM TableName Display the price SELECT fldPrice FROM tblCars; Display year and model SELECT fldYear, fldModel FROM tblCars; Display all car information SELECT* FROM tblCars; *Fields are retrieved in the order they are in the SELECT Statement

  19. Sorting Data – ODER BY Statement SELECT Field FROM TableName ORDER BY Field [ASC | DESC] Display the Model and Price … least expensive to most expensive SELECT fldModel, fldPrice FROM tblCars ORDER BY fldPrice; • Display the Price and Model* … most expensive to least expensive • SELECT fldPrice, fldModel FROM tblCars ORDER BY fldPrice DESC; • Display all information sorting by Make in ascending order and Price in descending order • SELECT * FROM tblCars ORDER BY fldMake, fldPrice DESC; *Fields are retrieved in the order they are in the SELECT Statement

  20. Restricting Data – WHERE Statement SELECT Field FROM TableName WHERE Criteria • < <= > >= = <> IN BETWEEN LIKE NOT • WHERE fldPrice > 2000 • WHERE fldPrice BETWEEN 5000 AND 10000 (Includes 5000 and 10000) • WHERE fldYear = 2010(If type is Year ~ no quotes needed) • WHERE fldDates> ‘2010-04-15’(If type is Date ~ enclose in single quotes) • WHERE fldModel LIKE ‘E%’(String enclosed in single quotes LIKE is used for pattern matching)

  21. Restricting Data – WHERE Statement LIKE - Pattern-matching Operator % Matches multiple characters_ Matches a single character WHERE fldModelLIKE ‘H%’; …Honda, Hyundai WHERE fldMakeLIKE‘H_ _ _ _’ ; …Honda WHERE fldMake= ‘O\’Hara’; If apostrophe is in the name (O’Hara), a backslash is required

  22. Restricting Data – WHERE Statement SELECT Field FROM TableName WHERE Criteria Display the Model and Price … cars over 10000 SELECT fldModel, fldPrice FROM tblCars WHERE fldPrice > 10000; Display the Year and Model… cars made in 2010 SELECT fldYear, fldModel FROM tblCarsWHERE fldYear = 2010; Display all information for cars whose Model begins with S SELECT * FROM tblCars WHERE fldModel LIKE ‘S%’;

  23. Restricting Data - DISTINCT Shows only unique fields, avoids redundancy SELECT DISTINCTFieldFROM TableName List the makes of cars, do not include name more than once SELECT DISTINCT fldMake FROM tblCars; RESULTS: With DISTINCT: Honda, HyundaiWithout DISTINCT: Honda, Hyundai, Honda

  24. Restricting Data - LIMIT Limits the number of records returned SELECT FieldFROM TableName LIMIT StartValue, NumRows; SELECT fldMake FROM tblCars LIMIT 0, 2;RESULTS: Start with the first record and display 2 records

  25. ActionQueries

  26. Action Queries Insert, Change, Delete Records • Does not retrieve a row • Performs operations on data • Returns a value indicating that operation was successfully completed

  27. Action Query -INSERT INSERT INTO Table(Fld1, Fld2, Fld3) VALUES (Val1, Val2, Val3) • Insert 2007, Red, and 10000 • INSERT INTO tblCars (fldYear, fldColor, fldPrice) VALUES (2007, ‘Red’, 10000) • *If the field was defined as date type as opposed to year type, the format would be ‘2007-04-15’.

  28. Action Query - DELETE DELETE FROM Table WHERE Criteria;DELETE * FROM Table WHERE Criteria; • Delete all cars made prior to 2010 • DELETE FROM tblCars WHERE fldYear < 2010 • Delete all black cars • DELETE FROM tblCars WHERE fldColor = ‘Black’;

  29. Action Query- UPDATE UPDATE Table SET fld1= NewValue, fld2=NewValue, etc.WHERE Criteria; • Increase the cost of all cars by 10% • UPDATE tblCarsSET fldPrice = fldPrice * 1.10; • Change the color of all red cars to maroonUPDATE tblCars SET fldColor = ‘maroon’ WHERE fldcolor = ‘red’ ;

  30. Variables in Queries Display Make $carMake = $_POST[“car_make"]; $SQLQuery = “SELECT fldMake FROM tblCars WHERE fldMake= ‘$carMake’ ”; $SQLQuery = “SELECT fldMake FROM tblCarsWHERE fldMake= ‘$_POST[“car_make"]’ ”; Insert a new record into the table $SQLQuery = “INSERT INTO tblCars (fldMake, fldModel, fldYear, fldColor, fldPrice) VALUES (‘$carMake’, ‘$carModel’, ‘$carYear’, ‘$carColor’, ‘$carPrice’)”;

  31. Primary Keys: Auto Increment If the Primary key is an auto-incremented field, use NULL for the insert value $SQLQuery = “INSERT INTOtblCars (fldID, fldMake, fldModel, fldYear, fldColor, fldPrice) VALUES (NULL,‘$carMake’, ‘$carModel’, ‘$carYear’, ‘$carColor’, ‘$carPrice’)”;

  32. TheEnd

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