{"id":6592,"date":"2020-04-16T11:43:48","date_gmt":"2020-04-16T11:43:48","guid":{"rendered":"https:\/\/www.garysieling.com\/blog\/?p=6592"},"modified":"2020-04-16T11:43:48","modified_gmt":"2020-04-16T11:43:48","slug":"postgres-sql-error-except-types-text-and-json-cannot-be-matched","status":"publish","type":"post","link":"https:\/\/www.garysieling.com\/blog\/postgres-sql-error-except-types-text-and-json-cannot-be-matched\/","title":{"rendered":"Postgres SQL ERROR: EXCEPT types text and json cannot be matched"},"content":{"rendered":"\n

Say you’re using the excellent Postgres JSON features. You may find that you get errors writing queries that use two tables – I often like to use “except” to diff datasets.<\/p>\n\n\n\n

If you write a SQL query like the following, you can get an error:<\/p>\n\n\n\n

with pre as (\n  select a, b from my_table\n), post as (\n  select re->'a', re->'b' from log\n)\nselect * from pre\n\nexcept\n\nselect * from post\n<\/pre>\n\n\n\n
While this looks like what you might want (the -> syntax looks intuitively correct), it uses the wrong operator, and you’ll get a type error:<\/p>\n\n\n\n
EXCEPT types text and json cannot be matched<\/p><\/blockquote>\n\n\n\n
The answer is to use the ->> operator rather than ->. The “->” is equivalent to lodash _.pick, whereas ->> is like doing object[key].<\/p>\n\n\n\n
<\/p>\n\n\n\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
Fixing a SQL error with Postgres JSON<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"footnotes":""},"categories":[4],"tags":[322,437,523],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t