If it's not for some reason to do with SQL's deeper architecture, I'd like to understand why. This feels like a more correct & less wasteful way to do it. In the past I've done operations like this by doing two SELECTS, one of which is against the item_templates table, the other against the unique_items table, and taken their UNION. PostgreSQL uses deterministic collation by default, which means that filtering is. Or if this is something you can't do conceptually - have each row choose its own join - I'd love to get a link to a deeper explanation. How Prisma Client handles case sensitivity when filtering and sorting. condition is an expression that returns a boolean result. ELSE result END CASE clauses can be used wherever an expression is valid. If there's a quick fix for the syntax, I'd love to hear it. The SQL CASE expression is a generic conditional expression, similar to if/else statements in other languages: CASE WHEN condition THEN result WHEN. This is the sort of thing I've been trying, without success: SELECT item_table, item_id, * So when I find a record of an item in the item_instances table, I want to look up more information about it, and I need to pull that info from the correct table. They are now stored in the unique_items table. Say I've got a table of item_instances in my game, of all the items in the game world, and some of the items are cookie-cutter copies of generic items from the item_templates table, and other items started off as templates, and then acquired unique properties as players used them. RAISE EXCEPTION 'Current date is %.I'm attempting to use a CASE expression to select which table each row should be joined with. IF right(pg_typeof($1)::text, 3) = to_char(_current_mon, 'mon') THEN The syntax of the IN operator is as follows: value IN (value1,value2.) Code language: SQL (Structured Query Language) (sql) The IN operator returns true if the value matches any value in the list i.e. to prevent incorrect column names, input row type must match current date: By default, SQL Server names are case insensitive. There are two forms of the CASE statement: Simple CASE statement Searched CASE statement Simple CASE statement Syntax: CASE search-expression WHEN expression1, expression2. Object name case sensitivity might be different for SQL Server and PostgreSQL. _current_mon timestamp := date_trunc('month', LOCALTIMESTAMP) PostgreSQL provides you with CASE statements that allow you to execute a block of code conditionally. Here is a proof of concept.īut, honestly, I'd rather avoid the complication and just use the simple query above.Ĭreate a polymorphic function: CREATE OR REPLACE FUNCTION f_tbl_counts_6months(ANYELEMENT) You want a simple call like this? SELECT * FROM f_tbl_counts_6months(NULL::m6_jul) But do you actually need the pivoted form? OK, you asked for it. Well, you could prepare 12 different row types (that's the range of possible result types for your case) and use a polymorphic function to achieve it. If you really need that, you need a 2-step flow of operation (two round trips to the server): But dynamic column names are not possible for a static SQL query. Your original query produces that information in pivoted form: one month per column. Using standard English month names and 3-letter-abbreviations. Query with LEFT JOIN not returning rows for count of 0.Note, in particular, that it's faster to aggregate first and join later. PostgreSQL: running count of rows for a query 'by minute'.COALESCE makes the count 0 instead of NULL for that case. This way always returns the last 6 months, even if no rows are found at all. Then LEFT JOIN to counts per month from the relevant time range. Generating time series between two dates in PostgreSQL.Note how I first build timestamps for the last six months (excluding the current one) with generate_series() in the first subquery mon. Returns one row per month, in chronological order (considering the year, too, though it's not in your output!), and truly dynamic. (I'd rather not use start as column name as that's a keyword in standard SQL - even if allowed in Postgres.) SELECT date_trunc('month', start) AS mon, count(*) AS ctĪND start = c.current_mon - interval '6 mon'
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