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sqlpostgresqljoinsql-update

How to update all the value from one column to another

Table 1 -

col1 col2
1 443
2 449
3 479

Table 2 -

col1 col2
1 NULL
2 NULL
3 NULL

Note - col1 is not a PK

expected Output -

Table 2 -

col1 col2
1 443
2 449
3 479

This is my python code:

abc_df = pd.read_sql_query("UPDATE Table1 SET Table1_id = t2.col1 FROM Table1 t1
                INNER JOIN Table2 t2 ON t1.col2 = t2.col2", con=connection)

But My Actual OUTPUT is -

Table 2 -

col1 col2
1 443
2 443
3 443
Solution

  • You need to update your UPDATE query -

    UPDATE Table2 T2
   SET col2 = T1.col2
  FROM Table1 t1
 WHERE T1.col1 = T2.col1