||Carlos Sierra developed the first version of this SQLTXPLAIN (SQLT) tool to help himself during the diagnostics of SQL statement performing poorly. On its first version its name was coe_xplain.sql and it was a simple script. After valuable feedback from several customers, coe_xplain.sql became SQLTXPLAIN (SQLT) and was adopted by a few EBS groups within Oracle. After some exposure to the server technologies team, SQLT became application independent and RAC aware. Today, on its third version, SQLT is widely used by many groups within Oracle, most notably by the query tuning group within support. It has become a preferred tool when the task at hand involves the root cause analysis for a SQL that performs poorly. Delivered by the author of this tool, this in-depth session explains and demonstrates how this SQLT tool helps to diagnose SQL statements performing poorly. It assumes nothing. The session covers SQLT from fundamental concepts, then installation, followed by main methods, SQLT reports navigation, and some special methods. Participants interested in hands-on experience will have the opportunity to practice most of the demos using their own databases either on their laptop or connected to their remote hosts if they can access them from the conference room. The session includes presentations, demos, and significant time for open questions.