SQL is a standard language for storing, manipulating and retrieving data in databases. Our SQL tutorial will teach you how to use SQL in: MySQL, SQL Server. Selecting MySQL Database - Learn MySQL from basic to advanced covering database programming clauses command functions administration queries and. (Under Windows, this restriction does not apply, although you must refer to databases and tables using the same lettercase throughout a given query. However.
|Published:||15 August 2014|
|PDF File Size:||45.77 Mb|
|ePub File Size:||3.55 Mb|
The above is the basic premise of a simple database table, even a real one having millions of records. More exotic databases link tables together relationally, so that specific values that might appear in hundreds of tables only need to be defined in one a topic to be covered later.
I've always thought that direct experience is a good way to inspire confidence in one's abilities, mysql database query we'll start out by creating a database and a table at mysql database query keyboard, by direct interaction with MySQL.
MySQL by Examples for Beginners
Because the procedure for installing MySQL is different on each platform, and because the installation process is nearly automatic in modern times, I've decided not to cover installation issues. At this point I mysql database query the reader has successfully installed MySQL and has logon authority in the system.
Start the MySQL command-line application I'll make this one concession to the differences between mysql database query If your MySQL installation is new, the list should be short: Now let's try generating an error — what happens if we try to create a database that already exists?
Can't create database 'tutorial'; database exists I should tell you that's one of the more informative MySQL error messages mysql database query most messages require the user to figure out what went wrong.
Now that we have created our database, let's tell MySQL to use it for subsequent entries: There's an alternative to telling MySQL which database to use — one simply prepends the database name to each table reference, like this: When dealing with multiple databases, this is often more convenient.
Make a Table In serious database work, one spends a fair amount of time in advance of table creation deciding what fields each table mysql database query should have, and what data types the fields should mysql database query.
PHP Select Data From MySQL
Mysql database query for this first effort, we'll limit ourselves to a simple table. In the entry below I have included a common error, to make the reader aware of an issue having to do with spaces.
You have an error in your SQL syntax; check the mysql database query that corresponds to your MySQL server version for the right syntax to use near 'Color text ' at line 1 Apart from showing the first of the dreaded and uninformative MySQL error messages, what's wrong?
Well, think about this — can MySQL figure out which parts of our entry are field names, and which are data types?
The first field name is "Name", and it has the data type "text". The field name and data type are separated by a space.
Selecting MySQL Database
But the field name "Favorite Color" has a space within it, and MySQL can't decide whether "Color" is part of the name or a data type, and there's no data type called "Color". So — error message, and no table.
Do be careful with commands like "drop mysql database query ". This table happens to be empty, but the same command works with a table having a million records — it just goes away mysql database query no warning.
Selecting MySQL Database
Now we have a table ready to accept records describing people by name, age and favorite color. It's time mysql database query insert some real data.
- MySQL Tutorial - MySQL By Examples for Beginners
- MySQL Tutorial 1: Overview, Tables, Queries
- Examples in Each Chapter
Again, I have deliberately introduced an error: But here's the correct entry: The name "Bruce Callow" is a string, a sequence of characters, so mysql database query must be enclosed in quotes of one kind or another. The age "13" is a number, so it doesn't need to be quoted.
But quoting a number is not an error, and in some cases, for consistency, all values might be enclosed in quotes.
The string "I haven't decided mysql database query contains an apostrophe. Unfortunately the apostrophe is also sometimes used as a quotation mark, which will confuse MySQL about where the string ends.