If you choose to reuse employee you might want to scrub away the bad data later. CREATE OR REPLACE FUNCTION coalescenonempty (VARIADIC inorderedactual varchar ) RETURNS varchar AS SELECT i FROM (SELECT unnest (1) AS i) t WHERE i IS NOT NULL AND i <> LIMIT 1 LANGUAGE sql Its pretty fast, but still nowhere as fast as COALESCE or CASE WHEN statements.
It also is not clear to me why you are inserting back into the employee table which has non usable data, rather than inserting into a new table. By using this, if there are no matching Person records, the FirstName will be displayed as an empty string instead of NULL. The consequence of the above is that, in oracle. select e.ModifiedDate, ISNULL (p.FirstName,'') as FirstName from Person.BusinessEntity as e left join Person.Person as p on e.BusinessEntityID p.BusinessEntityID. This means that the only operators you can apply to NULL values and that can return TRUE are 'is null' and 'is not null'. In oracle any comparison involving a NULL value will ALWAYS evaluate to FALSE. This assumes that your timestamp data is formatted as follows: DD/MM/YYYY HH:MI:SS PM (e.g. In Oracle the expression ('' is null) will evaluate to TRUE. Select 14, coalesce(to_timestamp(dojo, 'DD/MM/YYYY HH:MI:SS PM'), current_timestamp) Something like the following is what I believe you intend to do: insert into employee (eid, dojo) Instead, you should be using to_timestamp(), which can parse a string and return a timestamp. The output of to_char is a string, and the way you are using it would cause Postgres to reject it. As others have pointed out, one solution would be to use current_timestamp as a placeholder.Īnother problem you have is that you are incorrectly using to_char to format your timestamp data. This won't work, because empty string is not a valid timestamp. You can use COALESCE in conjunction with NULLIF for a short, efficient solution: COALESCE ( NULLIF (yourField,''), '0' ) The NULLIF function will return null if yourField is equal to the second value ( '' in the example), making the COALESCE function fully working on all cases: QUERY RESULT. First, you are trying to insert an empty string '' to handle NULL values in the dojo column. Example in my database with two different fields. However, once I'm getting this with node-pg, I get a string instead of a JSON empty array. PostgreSQL returns no particular error, and in pgadmin I'm getting in a JSONB type column. probably this was born as a bug, but today there is too much software that relies on this behaviour to fix it.Your current query has severals problems, two of which I think my answer can resolve. SELECT COALESCE(ak.singers, tojsonb(''::text)) AS singers. the only oracle function that treats null as a distinct comparable value is Decode(). So you must write it as update mytab set myfield='X' where myfield is null. So the following update will not update anything: update mytab set myfield ='X' where myfield = ''Īs I said, you can only use the 'is null' and 'is not null' operators. The consequence of the above is that, in oracle, ALL the following expressions will evaluate to FALSE, regardless of the actual value of myvar: myvar = ''Įven these evaluate always to false null = null This means that the only operators you can apply to NULL values and that can return TRUE are "is null" and "is not null" In oracle the empty string simply does not exist: it is just "syntax sugar" if you can write '' instead of NULL, when dealing with varchar values. In fact, I just tried to ALTER a table to change from NULL as default to empty string as default, and 1) it complained the there were NULL values there so I had to manually update to empty strings and 2) that triggered the 'Avoid assigning strings of zero length to character-type variables' warning in Toad. In Oracle the empty string is ALWAYS considered NULL: if you insert an empty string, you will read back a NULL. I don't know about postgres, but oracle has some quirks about empty strings you need to be aware about if you are planning to support it in your applications:
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