<p>In applying for jobs via agents I sometimes get blocked by an agent who says do you know software package X. When I reply that I know the similar package Y they might say unless you know X I cannot put you forward.</p>

<p>The problem is that some of these agents don't know what they talking about, they are merely being used by their clients as a screening filter.</p>

<p>It would be useful to be able to say to these agents that because I know Y I can expect to become reasonably proficient in X in a given number of days/months. However not knowing X determining the required time is why I'm asking this question.</p>

<p>Most recently X was Oracle and Y was SQL Server.</p>

<p>Please can those of you who know both, express an opinion on how long is required to become reasonably proficient? <strong>NB I'm not talking about becoming a DBA!</strong></p>

If you're being hired as a DBA, it will take a while to switch between databases as the management of them differs (I base this on my experience with Oracle and DB2 only).
I DON'T know SQL Server but I can imagine a Microsoft program with its nice GUI management would be vastly different to managing DB2/z, for example (although you can use the fancy DB2 LUW (Linux/UNIX/Window) tools if you're that way inclined).
If you're just cutting code to use the database, the SQL differences are minor (relatively).  That shouldn't take much time at all, assuming you're already proficient with SQL.