What does the * asterisk mean in a mysql statement?

Ex. mysql_query("SELECT * FROM members WHERE id='$id');
开发者_如何转开发

---

It means select all columns in the table.

---

It means that you are selecting every column in the table. This is something you should avoid in production environments though because it causes a bit of overhead and things tend to break when you alter your tables and use the * selector.

A better way to do this is to select only the columns you need each time, like the following example:

SELECT `id`, `firstName`, `lastName` FROM members WHERE id='$id'

---

Select ALL fields from some table.

---

It's a wildcard it means return all columns for that table in the result set.

---

It means "Select All", referring to all columns in referenced table. The issue with * relates to insert statements with existing tables or select statements used in a static report template. Any change in the referenced table would cause a change in the returned result set using *. If the insert or report source recordset has any additional or missing columns, the query may break. The main point is that using * can give you inconsistent columns and recordsets.