Share PHP error prompt explanation_PHP tutorial

When learning PHP, I often encounter various error prompts. It feels good to see this error prompt and explanation today. I now turn it over for us to learn from. hehe. . . . .
1. Notice: Undefined variable: Variable name in
Note: An undefined variable is used
2. Parse error: syntax error, unexpected T_ELSE in
If () {
}Else if () {
}
Echo $test;
Else {
}
Note: The if else if else sentence structure is wrong
3. Parse error: syntax error, unexpected $end in D
Note: Usually the curly braces do not match
4. Parse error: syntax error, unexpected T_STRING in
Note: Usually I forget to write the semicolon
at the end of the sentence 5. Warning: Invalid argument supplied for foreach() in
Note: The first parameter of foreach must be an array
6. Warning: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource in
Note: This means that the previous execution of SQL failed to return. Generally, it may be an error in the SQL statement. If the analysis does not come out, you can just print out Mysql_error (); to see where the error is specifically
7. No database selected
Note: Usually there is no connection to the database
8. Warning: mysql_connect() [function.mysql-connect]: Access denied for user ‘root’@’localhost’(using password: YES) in ….. on line 3
Access denied for user ‘root’@’localhost’ (using password: YES)
Note: The database username and password are wrong
9. Unknown database ‘cms07261′
Note: There is no such database
10. Table ‘cms0726.test’ doesn’t exist
Note: The table does not exist
11. Unknown column ‘abc’ in ‘field list’
Note: The field does not exist
12. Column count doesn’t match value count at row 1
Note: The number of field values ​​in the sql statement is different from the number of field names
13. Warning: Wrong parameter count for function name in
Note: The number of function logarithms is missing
14. Fatal error: Smarty error: [in message_list.html line 22]: syntax error: ‘foreach: item’ must be a variable name (literal string)
Note: Looking at the line number, it means that the item after foreach must be followed by a variable name, without adding $, it is a string (note: there are no single or double quotes)
15. Fatal error: Smarty error: [in message_list.html line 24]: syntax error: unrecognized tag: msg.message_id
Note: $
is missing before the variables in the template 16.
Warning: Smarty error: unable to read resource: “message_list1.html” in
Note: The template file cannot be found. Check whether the file name is written incorrectly or the file is stored in another directory.
17. Fatal error: Cannot redeclare get_sort1() (previously declared in
Note: The function has been defined and cannot be redefined