![]() ![]() ![]() Learn more about PostgreSQL in the Xojo Dev Center. If you use a tool’s UI to create a table and have a habit of typing in mixed case, the tool might generate SQL (or even the table itself) for you using quotes, which as you can see could mess you up later. Obviously that can start to become a bit of a pain, so the moral of the story is don’t use quotes when creating tables or writing SQL queries so that everything is created as lowercase and things will work like you probably expect. You’ll especially want to pay attention to any tools you use to create SQL for you. To avoid this error you instead have to write the SQL with quotes like this: SELECT "FullName" FROM "Person" This is because PostgreSQL is converting “Person” to “person”, but there is no table called “person”. Now what happens if you try to run a query with a table called “Person”? Well, using SQL like this: SELECT FullName FROM Person ![]() This means you’ll get a table called “Person” with two columns called “FullName” and “Address”. In the last example, the names are in quotes so their case is maintained. In the first two examples, you get a table called “person” with two columns called “fullname” and “address”. That may not be obvious in the second example since the names are not lowercase, but remember that PostgreSQL converts your SQL to lowercase for you. For example, consider these SQL CREATE statements: CREATE TABLE person (fullname VARCHAR(100), address VARCHAR(100)) CREATE TABLE Person (FullName VARCHAR(100), Address VARCHAR(100)) CREATE TABLE "Person" ("FullName" VARCHAR(100), "Address" VARCHAR(100)) ![]() That is nice if you happen to like to write your queries with mixed casing.īut you’ll start to run into a problem if you’ve actually created the table with case-sensitive names, which happens when you use quotes around the names. This gets converted to: SELECT fullname FROM person So take a look at this SQL: SELECT FullName FROM Person What it actually does is convert your SQL to lowercase by default. Sometimes you hear that PostgreSQL is case-insensitive, but it isn’t really. WHERE fuel_descriptions.I’ve ran into PostgreSQL case sensitivity myself before and I’ve seen it come up on the forums, so I thought it might be a good thing to bring up here. LEFT JOIN dailywx ON px_f_weathercell.fid_new_wx_cells = dailywx.location LEFT JOIN f_descriptions ON px_f_weathercell.px_id = f_descriptions.fuel_id WHEN 'SUNNY' then dailywx.hoursabove4k_sunny I'm still recieving null values from the CASE statement, however. This has resulted in 100,000 records returning in approx 5-7 seconds. I've also set an index on px_f_weathercell.fid_new_wx_cells and px_f_weathercell.px_id. I've also used PGTune to set some recommended settings in order to address a situation where the process was disk bound. Both columns are of type double.ĮDIT2: Updated a couple of table names to indicate where columns are coming from. Made the following edit, no getting a column full of nulls when the column desired has numbers (including 0) in it. The error is as follows: ERROR: syntax error at or near "CASE"īonus points: CASE seems slow. WHERE best_model_fit = 'SUNNY' /* limiting my test case here, clause will be removed later */ INNER JOIN dailywx ON px_f_weathercell.fid_new_wx_cells = dailywx.location INNER JOIN f_descriptions ON px_f_weathercell.px_id = f_descriptions.fuel_id I'm going to guess that my INNER JOIN and CASE statements are back to front, but I'm not sure how to rearrange them without breaking the intent.īasically: Where model_best_fit = SUNNY, then I'd like a new column with name applied_f_model_hours_above4k to have the value from the column hoursabove4k_sunny I'm left joining three tables, and would like to be able to use a case statement to introduce another column that brings across a desired value from one column based on another. from ( select CASE WHEN accountid IS NOT NULL THEN value ELSE value2 END AS result. You have to use a derived table: select result, result as result2. I'm a Postgresql newbie, so still struggling a little bit here. 1 Answer Sorted by: 0 You can't use a column alias on the same level where you define it. ![]()
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