[newbie] help with sql query

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      Hi,
           I was on the look out a for a single query for the
following
      problem:.

      We have three tables as Table1, Table 2, and Table3 having a
common
      column "key12" between Table1 and Table2, and a common column
"key23"
      between Table2 and Table3.

      So
      Table 1 consists of ( Key 12, Heading, Data1)
      Table 2 consists of ( Key 12, Key 23,  Data2)
      Table 3 consists of ( Key 23, Heading, Data3)

      If we execute a query based upon key12 between Table1 and
Table2, it
      returns multiple rows. (Say Result 12)

      Now we want to execute a query based upon key 23 between Table 3
and
      Result 12 (obtained earlier) and display Data3

      How to accomplish this all in a single nested query ?

      Your help will be highly appreciated.

      Very Best regards,
      adi