Monthly Archives: January 2011

Helpful Tips

MySQL: Drop all tables with prefix

1 Comment

I use the mysql command line tool to administrate my MySQL. I needed a quick way to drop all tables with the following prefix.

SELECT CONCAT('DROP TABLE `', TABLE_SCHEMA, '`.`', TABLE_NAME, '`;') FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME LIKE 'prefix%' and TABLE_SCHEMA = 'dbname';

Then all you have to do is take a text editor and replace all the “|” signs around the result.

PS: As you can see the query can be modified to get all tables with suffix, or all tables in a schema, or TRUNCATE all tables in the criteria.

Programming

Coldfusion Cfform bug/error: “_b is undefined”

4 Comments

While coding a HTML form using Coldfusion’s CFForm, I encountered a bug that threw a javascript error while submitting it.

"_b is undefined" from cfform.js

around line 3:

_CF_hasValue=function(_b,_c,_d){
if(_c=="TEXT"||_c=="FILE"||_c=="PASSWORD"||_c=="CFTEXTAREA"||_c=="TEXTAREA"||_c=="CFTEXTINPUT"||_c=="DATEFIELD"){
if(_b.value.length==0){
return false; 
}else{
if(_d){
str=_b.value.replace(/^\s+/,"").replace(/\s+$/,"");
if(str.length==0){
return false;
}
}

One of the problems with errors while submission is that it happens very quickly and the browser redirects. So the user doesn’t see the javascript error. It also breaks execution of any (onsubmit/event) javascript code.

I went through my cfform to find any problems code. However at the end, I noticed that the cfform tag was missing the “name” attribute, and by simply adding the “name” attribute I was able to avoid the error.

This is one of the reasons I do not like ColdFusion’s helpers, because the errors that they sometimes generate are very misleading and not documented.