I have built queries with many CTE to progressively build up data for complex reporting and find it a far more efficient way of coding which can be easily tested level by level. SELECT * FROM Cit8 LEFT OUTER JOIN SourceTable ON CitationTable.SourceID = SourceTable.SourceID So a simple list of citations with their sources becomes: With Cit8 as Then continue with original query but change all occurrences of CitationTable to Cit8 (Select c.CitationID, cl.OwnerType, cl.OwnerID, c.SourceID, cl.Quality, cl.IsPrivate, c.Comments, c.ActualText, c.RefNumber, cl.Flags, c.Fieldsįrom CitationTable c INNER JOIN CitationLinkTable cl The CitationTable from version 7 has been split into CitationTable and CitationLinkTable in version 8 but using a CTE we can emulate the version 7 structure then just change the table name in the main query. With the database changes between RM7 and RM8 the CTE is most useful to convert queries written for version 7 to run against a version 8 database. By altering the where clause this can list facts without citations or facts not marked proven (or both).
Rootsmagic 7 delete parent full#
My full query example attached is a list of facts and their citations, including the owner (person or family). Putting it in a CTE gets it out of the way, leaving the main query readable.
![rootsmagic 7 delete parent rootsmagic 7 delete parent](https://www.tamurajones.net/img/screens/RM6DualTimeLineView.png)
Rootsmagic 7 delete parent code#
The date expansion code is longwinded and distracting from the main query. There is also a RIGHT OUTER JOIN and a FULL OUTER JOIN but SQLite does not support these constructs.Īnother useful implementation of the CTE is to expand out tables in RM that contain dates and fields that need collation changes. Inner JOIN and just plain JOIN would leave out records which do not have a match for the person id and an owner type of 0 and in fact the whole query would just mess up.Ī good rule for SQL readability is to always fully specify the join type so never use just JOIN but always INNER JOIN or LEFT OUTER JOIN. Note the left outer join syntax which allows all records from the left hand table to be included even if there is not a matching record on the right hand side. WITH a AS (something), b AS (something else), c AS (something more) SELECT ………. * and (ev.Proof = 0) – not proven (remove surrounding comment markers /* and */ to include this restriction)*/ WHERE ev.EventType 35 /* ignore reference numbers */ * join in the family persons for owner type = family */Įv.OwnerID = fam.FamilyID and ev.OwnerType = 1 So I can add another CTE to get both parent details for a family and this can (but does not have to) use the first CTE.Īll this happens before the main query and the main query simply uses those CTE as if they were tables.Ĭase when ev.OwnerType = 1 THEN fam.SurnameĬase when ev.OwnerType = 1 THEN fam.Givenįrom ev /* join in person where owner type is person */Įv.OwnerID = pers.RIN1 and ev.OwnerType = 0 A query can contain multiple CTE and once the first has been declared, subsequent CTE are declared by continuing the WITH clause and putting This is just a simple example using a CTE once. So you can see pers is treated as if it were another table or view in the query. Now I have an item I can use in the rest of my query so that continues: SELECT CTE names are best kept short as they will be used further on in the query. Then the name of the CTE is declared folowed by AS then its definition in brackets.
![rootsmagic 7 delete parent rootsmagic 7 delete parent](https://pbs.twimg.com/profile_images/537590500740460548/oxwdNWOc_400x400.png)
![rootsmagic 7 delete parent rootsmagic 7 delete parent](https://familyhistorydaily.com/wp-content/uploads/2018/01/Family-View-RootsMagic.png)
The very first word of the first CTE has to be WITH and this has to be the very start of the query, apart from comments. NameTable.Surname COLLATE NOCASE AS Surname, The CTE is declared at the start of a query using the WITH construct so I can write: WITH pers AS Views could also be created but that involves a physical object within the database being created and remembering to tidy up and delete it later. Yes, subqueries do the same thing but a CTE can be used repeatedly in the query after it has been declared without further re-declaration whereas a sub-query has to be declared every time it is used. Common Table Expressions (CTE) are a feature that was first introduced to SQL in about 2005 and provide a method of defining a temporary result set then using that in the query as if it were another table.