Brief introduction of MySQL statement annotation mode

MySQL supports three annotation modes:

1. From the '#' character from the end of the line.

2. From the '--' sequence to the end of the line. Note that the '--' (double dash) annotation style requires that the second dash be followed by at least one space character (such as space, tab, line break, etc.).

3. From the /* sequence to the following */sequence. The ending sequence is not set in the same line, so this syntax allows comments to span multiple lines.

The following example shows three styles of annotations:

// In mysql How to write comment statements in 
mysql> SELECT 1+1;   #  This comment is made until the end of the line 

mysql> SELECT 1+1;   --  This comment is made until the end of the line 

mysql> SELECT 1 /*  This is 1 A comment in the middle of the line  */ + 1;
mysql> SELECT 1+
/*
 This is 1 A 
 The form of multi-line comments 
*/
1;

The above annotation syntax applies to how the mysqld server parses SQL statements. The mysql client also performs partial statement parsing before sending it to the server. (For example, it resolves to determine statement boundaries in multiple statement lines).

Summarize

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