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--- v5:userguide:learn_abstraction:start_lesson [2016/03/15 01:08] – created mnewnham
+++ v5:userguide:learn_abstraction:start_lesson [2016/08/13 15:44] (current) – [Introduction] mnewnham
@@ Line 1: / Line 1: @@
-====== The Database Abstraction Layer ======
+<- v5:userguide:learn_abstraction:introduction|The Database Abstraction Layer ^ v5:userguide:learn_abstraction:introduction|Start Of Lesson ^ v5:userguide:learn_abstraction:establishing_connection|Establishing A Connection ->
 ~~NOTOC~~
-===== Table Of Contents =====
+====== Introduction ======
-<doctoc start=v5:userguide:learn_abstraction:start_lesson, useheading=1, includeheadings=1-5>
+ADOdb is a **Database Abstraction Layer** that allows the writing of database independent SQL statements. It does this by placing a layer of generic statement execution code between the programmer and the PHP database-specific access commands. This allows the writing of portable SQL code that can access multiple databases. For example the following database specific statements:
-===== Other Guides =====
-[[v5:reference:reference_index|Reference Guide]]\\
-[[project:include_file_guide|Include File Guide]]\\
-[[v5:userguide:portable_sql|Writing Portable SQL]]\\
-[[v5:userguide:mysql_tutorial|Migrating MySQL applications to ADOdb]]\\
-[[v5:userguide:error_handling|Customizing Error Handling]]\\
-[[v5:userguide:stored_procedure|Stored Procedure Example]]\\
-[[v5:userguide:deprecated|Deprecated Functionality]]\\
-===== Introduction =====
+  MySQL         mysqli_execute
-ADOdb is a **Database Extraction Layer** that allows the writing of database independent SQL statements. It does this by placing a layer of generic statement execution code between the and the programmer and the PHP database specific database access commands. This allows the writing of portable SQL code that can access multiple databases. For the example the following database specific statements:
+  Oracle        oci_execute
+  SQL Server    mssql_execute
-  MySQL      mysqli_execute
-  Oracle     oci_execute
-  SQL Server mssql_execute
 can all be replaced by a single ADOdb replacement [[v5:reference:connection:execute|execute()]]. In addition, ADOdb provides a number of shortcut commands to commonly used SQL syntax.
-ADOdb is not a replacement for the  database driver, which must be installed and correctly configured.
+ADOdb is not a replacement for the PHP database driver, which must be installed and correctly configured. If it is not, ADOdb will immediately issue an error message **//Driver Not Installed//** when a connection is attempted. The best way to debug the problems is to bypass ADOdb completely and work on establishing a connection with the database directly through the PHP level driver. Once the connection is established that way, ADOdb should work correctly. There are many reasons why the driver cannot connect. The best place to obtain help is on sites like StackOverflow and database manufacturers forums
-<- v5:userguide:learn_abstraction:start_lesson|Start Of Lesson ^ v5:userguide:learn_abstraction:start_lesson|Start Of Lesson ^ v5:userguide:learn_abstraction:establishing_connection|Establishing A Connection ->