<script language="javascript">
function textCounter(field, maxlimit) {
if (field.value.length > maxlimit)
field.value = field.value.substring(0, maxlimit);
else if (field.value!=null)
{
var Sql_1 = " and | exec | count | chr | mid | master | or | truncate | char | declare | join |'|<|>|/*|*/|;|insert|select|delete|update|create|drop";
var sql_c = Sql_1.split('|');
for(var index=0;index<sql_c.length;++index)
{
if (field.value.indexOf(sql_c[index]) != -1) {
field.value="";
alert("包含非法关键字,请重新输入!");
}
}
}
}
</script>
再在相应TextBox加 onPropertyChange="textCounter(this,50)"