The “join” function is used to connect different tables in M3. Any report containing information in more than one table requires a join. For example, since the item Title and Author are stored in the M3Bibliographic table and the Call Number is stored in the M3Holding table, a report containing this information requires a join.
A join can only be performed between tables that contain a field with common data. For example, all records in the M3Bibliographic table contain an ISN number (Control Number), which is contained in M3Bibliographic.001. The M3Holding table also contains an ISN number, which is contained in M3Holding.001. How- ever, these ISN numbers are not equal. The M3Holding table also contains a field which stores the ISN number for the corresponding bibliographic record. The bib- liographic ISN is stored in the M3Holding.004 field. Therefore, when creating a join between the bibliographic table and the holding table, the join is M3Bibliographic.001 >>> M3Holding.004.
Table 7.1 lists the joins most commonly used when creating reports for M3.
