How many types comment lines exist in SQL?

Are there comments in SQL?

In SQL, you can comment your code just like any other language. Comments can appear on a single line or span across multiple lines.

What is comment line in SQL?

You can comment out or uncomment a single line of code in an SQL statement, multiple adjacent lines of code, a complete SQL statement, or multiple adjacent SQL statements. The syntax for a comment in a line of SQL code is a double hyphen ( — ) at the beginning of the line.

How do you comment in SQL Workbench?

In MySQL, a comment started with — symbol is similar to a comment starting with # symbol. When using the — symbol, the comment must be at the end of a line in your SQL statement with a line break after it. This method of commenting can only span a single line within your SQL and must be at the end of the line.

How do I comment in SQL access?

#Syntax Using — Symbol

The syntax for creating the comment in SQL using — symbol is the following. Any text between — and the end of the line will be ignored (will not be executed). The comment started with — symbol must be at the end of the line in your SQL statement with the line break after it.

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How do I comment in spark SQL?

For single line comment we should use — and for multiline /* comments */ . Actually comment is working in your case, problem is – spark ignores those comments after that it looks for sql commands but you didn’t specify any. Below code will throw error.

How can we write comment in SQL?

Comments

  1. Begin the comment with a slash and an asterisk (/*). Proceed with the text of the comment. This text can span multiple lines. End the comment with an asterisk and a slash (*/). …
  2. Begin the comment with — (two hyphens). Proceed with the text of the comment. This text cannot extend to a new line.

How do I comment multiple lines in Oracle SQL Developer?

6 Answers. In SQL Developer, I highlight all lines of PL/SQL that I want commented and use Ctrl + / . Obviously, you would like a way to comment and uncomment multiple lines quickly. This will put — in front of each line you have highlighted.

Where do we use commit in SQL?

Use the COMMIT statement to end your current transaction and make permanent all changes performed in the transaction. A transaction is a sequence of SQL statements that Oracle Database treats as a single unit. This statement also erases all savepoints in the transaction and releases transaction locks.

What are the three SQL classifications?

Data Definition Language (DDL) Statements. Data Manipulation Language (DML) Statements. Transaction Control Statements.

What is the full form of DML?

A data manipulation language (DML) is a computer programming language used for adding (inserting), deleting, and modifying (updating) data in a database.

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How do I comment multiple lines in SQL?

MySQL supports three comment styles:

  1. From a ‘– ‘ to the end of the line. The double dash-comment style requires at least whitespace or control character (space, tab, newline, etc) after the second dash. …
  2. From a ‘#’ to the end of the line. …
  3. C-style comment /**/ can span multiple lines.

Why we can use like commands?

The MySQL LIKE condition allows wildcards to be used in the WHERE clause of a SELECT, INSERT, UPDATE, or DELETE statement. This allows you to perform pattern matching.

How do I write an if statement in MySQL?

MySQL IF() Function

  1. Return “YES” if the condition is TRUE, or “NO” if the condition is FALSE: …
  2. Return 5 if the condition is TRUE, or 10 if the condition is FALSE: …
  3. Test whether two strings are the same and return “YES” if they are, or “NO” if not: