title: Oracle SQL: Update with variable table name and fixed column name
body: <p>I am a beginner with SQL and have a problem: 
  I have a DB with a big number of tables. Some of the tables have a column with the name "lab". 
  In this colums are values I need to be changed. </p>
  
  <p>So I managed to get the names of the tables via </p>
  
  <pre><code>SELECT CNAME,TNAME FROM SYSTEM.COL WHERE CNAME = 'LAB';
  </code></pre>
  
  <p>And I know my update command</p>
  
  <pre><code>update TNAME set LAB='VALUE' WHERE LAB='OLDVALUE' 
  </code></pre>
  
  <p>But I can not manage to connect both statements via a variable TNAME or something. I tried to use execute immediate, but that did me no good. </p>