QlikView Reference Manual.pdf - QlikCommunity - QlikView

Forced Concatenation
If two or more tables do not have exactly the same set of fields, it is still possible to force QlikView to concatenate
the two tables. This is done with the concatenate prefix in the script, which concatenates a table
with another named table or with the last previously created table.
Example:
load a, b, c from table1.csv;
concatenate load a, c from table2,csv;
The resulting internal table has the fields a, b and c. The number of records in the resulting table is the sum
of the numbers of records in table 1 and table 2. The value of field b in the records coming from table 2 is
NULL.
Rules:
l The names of the fields must be exactly the same.
l Unless a table name of a previously loaded table is specified in the concatenate statement the concatenate
prefix uses the last previously created table. The order of the two statements is thus not arbitrary.
Preventing Concatenation
If the field names and the number of fields of two or more loaded tables are exactly the same, QlikView will
automatically concatenate the content of the different statements into one table. This is possible to prevent
with a nonconcatenate statement. The table loaded with the associated load or select statement will then not
be concatenated with the existing table.
Example:
load a, b, c from table1.csv;
nonconcatenate load a, b, c from table2.csv
26.8 Join and Keep
It is possible to join tables already in the script. The QlikView logic will then not see the separate tables,
but rather the result of the join, which is a single internal table. Sometimes this is preferable, sometimes even
necessary, but most of the time it is not advisable, since:
l The loaded tables often become larger, and QlikView works slower.
l Some information may be lost: the frequency (number of records) within the original table may no
longer be available.
The keep functionality, which has the effect of reducing one or both of the two tables to the intersection of
table data before the tables are stored in QlikView, has been designed to reduce the number of cases where
explicit joins needs to be used. .
Note!
In this manual the term join is usually used for joins made before the internal tables are created. The association,
made after the internal tables are created, is however essentially also a join.
Joins within an SQL Select Statement
With some ODBC drivers it is possible to make a join within the select statement. This is almost equivalent
to making a join using the join prefix.
However, most ODBC drivers are not able to make a full (bidirectional) outer join. They are only able to
make a left or a right outer join. A left (right) outer join only includes combinations where the joining key
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