Add a section about statements logging/debugging

README.md

@@ -362,6 +362,29 @@ The default built-in `Codec`s  reference table shows the type mapping between [M
 | `JSON` | - | [**`String`**][java-String-ref], `Clob` |
 | `GEOMETRY` | - | **`byte[]`**, `Blob` |
 
+## Statements Logging/Debugging
+
+Use the `io.asyncer.r2dbc.mysql.QUERY` logger and the `DEBUG` log level to log statements and their bound
+parameters (if it is prepared statement).
+
+For example, in `logback.xml`:
+
+```xml
+<configuration>
+    <!-- ... -->
+    <logger name="io.asyncer.r2dbc.mysql" level="INFO"/> <!-- or DEBUG if necessary -->
+    <logger name="io.asyncer.r2dbc.mysql.QUERY" level="DEBUG"/>
+    <!-- ... -->
+</configuration>
+```
+
+Note that it will print the SQL statement and all parameters, so this may be a security risk. Don't use it
+in an environment with sensitive data. It should be used for debugging purposes only.
+
+The log format may be different for server-preparing and client-preparing. This is because the actual
+generated statements and commands are different in these two modes. For example, a server-preparing statement
+has its statement ID that's generated by server, but client-preparing does not.
+
 ## Add a `Codec`
 
 This is an extension of a highly customized driver behavior of encoding parameter or decoding field data.