Which is the comment symbol in MySQL?

In MySQL, a comment that starts with /* symbol and ends with */ and can be anywhere in your SQL statement. This method of commenting can span several lines within your SQL.

How many fields should a database have?

9 Answers. The design of the table depends on the entity it needs to store. If all the data belongs together, then 50 columns (or even 100) might be the correct thing to do. So long as the table is normalized, there is no rule of thumb regarding size, apart from database capabilities and the need to optimize.

How do I add comments to a table in MySQL?

The comments can be added to the MySQL columns while creating a table by adding the COMMENT keyword after the column definition, as shown above for column emp_name. The table is created successfully with comments. Confirm the same in column information using MySQL workbench.

How do I comment in MySQL workbench?

MySQL Server supports three comment styles: From a # character to the end of the line. From a — sequence to the end of the line. In MySQL, the — (double-dash) comment style requires the second dash to be followed by at least one whitespace or control character (such as a space, tab, newline, and so on).

What are the pitfalls of Rdbms?

Drawbacks or disadvantages of RDBMS ➨Complex software refers to expensive hardware and hence increases overall cost to avail the RDBMS service. ➨It requires skilled human resources to implement. ➨Certain applications are slow in processing. ➨It is difficult to recover the lost data.

What should be in a database?

A good database design is, therefore, one that:

• Divides your information into subject-based tables to reduce redundant data.
• Provides Access with the information it requires to join the information in the tables together as needed.
• Helps support and ensure the accuracy and integrity of your information.

How many columns can MySQL table have?

4096 columns
MySQL has hard limit of 4096 columns per table, but the effective maximum may be less for a given table. The exact column limit depends on several factors: The maximum row size for a table constrains the number (and possibly size) of columns because the total length of all columns cannot exceed this size.

How many columns should be in a database table?

For the columns in a table, there is a maximum limit of 1024 columns in a table. SQL Server does have a wide-table feature that allows a table to have up to 30,000 columns instead of 1024.

What is a comment in MySQL?

In MySQL, a comment that starts with /* symbol and ends with */ and can be anywhere in your SQL statement. This method of commenting can span several lines within your SQL.

How do you comment on a single line in SQL?

This method of commenting can only span a single line within your SQL and must be at the end of the line. Syntax Using /* and */ symbols. The syntax for creating a SQL comment in MySQL using /* and */ symbols is: In MySQL, a comment that starts with /* symbol and ends with */ and can be anywhere in your SQL statement.

How to show a comment that spans across multiple lines in MySQL?

This SQL comment spans across multiple lines in MySQL – in this example, it spans across 5 lines. In MySQL, you can also create a SQL comment that spans multiple lines using this syntax: SELECT contact_id, last_name, first_name /* Author: TechOnTheNet.com Purpose: To show a comment that spans multiple lines in your SQL statement. */ FROM contacts;

What is the use of SELECT statement in MySQL?

MySQL queries mostly starts with SELECT statement. This query shows the current date and time. This executes SELECT statement without any table. SELECT can be used for executing an expression or evaluatin an in-built function.