Skip to main content

INSERT with NULL Values


In general, if a column has no default value, the effect of omitting it from the INSERT depends on
whether it can take NULL values and SQL mode being used:

􀂃 If the column can take NULL values, it is set to NULL.

􀂃 If the column cannot take NULL values, it is set to the implicit default for the column data type if
strict SQL mode is not enabled. If the strict mode is enabled, an error occurs.

􀂃 To get the next available number in an AUTO_INCREMENT column, leave the column out of the
column list, or give it the value of NULL in the value list. The same applies to TIMESTAMP type
columns.
Labels:

Comments

Post a Comment

Popular posts from this blog

PHP INTRODUCTION

                     PHP  (recursive acronym for  PHP: Hypertext Preprocessor ) is a widely-used open source general-purpose scripting language that is especially suited for web development and can be embedded into HTML. PHP stands for  P HP:  H ypertext  P reprocessor PHP is a server-side scripting language, like ASP PHP scripts are executed on the server PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc.) PHP is an open source software PHP is free to download and use Why PHP? PHP runs on different platforms (Windows, Linux, Unix, etc.) PHP is compatible with almost all servers used today (Apache, IIS, etc.) PHP is FREE to download from the official PHP resource:  www.php.net PHP is easy to learn and runs efficiently on the server side What can PHP do? Anything. PHP is mainly focused on server-side scripting, so you can...
6 comments
Read more

SQL Joins

1. Login in to the mysql client using the login name and password provided by your instructor (if not already logged in). 2. View the existing databases that the MySQL Server is maintaining. SHOW DATABASES; 3. Utilize the photo_album database. USE photo_album; ---- If Need be, recreate the database and load the SQL data in that will be used for this lab CREATE DATABASE photo_album; SOURCE /tmp/photo_album.sql; 4. Query the database to display the active primary customer (email, first and last name) and all the associated active login names associated with that customer. SELECT customers.email_customer, customers.fname, customers.lname, logins.login_name  FROM customers, logins WHERE customers.email_customer = logins.email_customer  AND customers.active_customer = 'True'  AND logins.active_login = 'True';
Post a Comment
Read more

Self Joins

A table name is always ambiguous when table is joined to itself using a self-join. For example, the Country table in the world database contains an IndepYear column indicating the year in which each country achieved independence. To find all countries that have the same year of independence as some given country, a self-join can be used. However, the query cannot be written like this: mysql> SELECT IndepYear, Name, Name -> FROM Country JOIN Country -> ON IndepYear = IndepYear AND Name = 'Qatar'; ERROR 1066 (42000): Not unique table/alias: 'Country' Furthermore, the ambiguity cannot be removed from column references by preceding them with table name qualifiers because the names remain identical: mysql> SELECT Country.IndepYear, Country.Name, Country.Name -> FROM Country JOIN Country -> ON Country.IndepYear = Country.IndepYear -> AND Country.Name = 'Qatar'; ERROR 1066 (42000): Not unique table/alias: 'Country' It ...
Post a Comment
Read more