Combining four tables in SQL Server -
i have 4 tables table a
, table b
, table c
, table d
. schema of 4 tables identical. need union
these 4 tables in following way:
if record present in
table a
considered in output table.if record present in
table b
considered in output table if not present intable a
.if record present in
table c
considered if not present intable a
,table b
.if record present in
table d
considered if not present intable a
,table b
, ,table c
.
note -
every table has column identifies table every record (i don't know if of importance)
records identified based on particular column -
column x
not unique within each table
you (only 2 cases shown should see how extend this)
with cte1 ( select 't1' source, x, y t1 union select 't2' source, x, y t2 ), cte2 ( select *, rank() on (partition x order case source when 't1' 1 when 't2' 2 end) rn cte1 ) select x,y cte2 rn=1
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