postgresql

问题 I am importing Excel data into postgreSQL using Python and running into an Programming Error. I did research the issue and found out it has something to do with postgreSQL. Can someone please provide assistance. import psycopg2 import xlrd book = xlrd.open_workbook("T:\data.xlsx") sheet = book.sheet_by_name("HCSData") database = psycopg2.connect (database = "", user="") cursor = database.cursor() delete = """Drop table if exists "Python".hcsdata""" print (delete) mydata = cursor.execute

问题 I can't get information of that simple question over the PostgreSQL documentation, over the Web or even here on StackOverflow... I must not unsertand something essential here. I am making a simple SELECT / UPDATE transaction in PostgreSQL: START TRANSACTION; SELECT "column" FROM "table" WHERE "criterion" = 'value' AND "activated" = true; UPDATE "table" SET "activated" = false WHERE "criterion" = 'value'; COMMIT Basically, I need to get the value of a column when its activated state is true

问题 I can't get information of that simple question over the PostgreSQL documentation, over the Web or even here on StackOverflow... I must not unsertand something essential here. I am making a simple SELECT / UPDATE transaction in PostgreSQL: START TRANSACTION; SELECT "column" FROM "table" WHERE "criterion" = 'value' AND "activated" = true; UPDATE "table" SET "activated" = false WHERE "criterion" = 'value'; COMMIT Basically, I need to get the value of a column when its activated state is true

问题 I'm currently trying to insert in batch many records (~2000) and Jooq's batchInsert is not doing what I want. I'm transforming POJOs into UpdatableRecords and then I'm performing batchInsert which is executing insert for each record. So Jooq is doing ~2000 queries for each batch insert and it's killing database performance. It's executing this code (jooq's batch insert): for (int i = 0; i < records.length; i++) { Configuration previous = ((AttachableInternal) records[i]).configuration(); try

问题 Considering the following example select * from foo where time +'10 day' >current_timestamp I would like to make this query parametrized for Java, and I don't know how to set the 10 day ?! (String doesn't work) 回答1: select * from foo where time +'10 day'::interval >current_timestamp; 回答2: You may either pass a String parameter and cast it, e.g. select * from foo where (time + CAST(? AS interval)) > current_timestamp or pass an int parameter multiplied by a fixed interval, which is better if

问题 psql has a construct for passing named arguments: psql -v name='value' which can then be referenced inside a script: SELECT :name; which will give the result ?column? ---------- value (1 row) During development, I need to drop and recreate copies of the database fairly frequently, so I'm trying to automate the process. So I need to run a query that forcibly disconnects all users and then drops the database. But the database this operates on will vary, so the database name needs to be an

问题 There is a constraint violation handling "On conflict" statement, working fine if i want to check 1 (!) constraint For example : INSERT INTO my_table (co1,col2..colN) VALUES (...) ON CONFLICT (col1, col2) DO NOTHING --or update But if i have 2 constaints unique(col1,col2) and unique(col5,col6,col7) , the query below is not working : INSERT INTO my_table (co1,col2..colN) VALUES (...) ON CONFLICT (col1, col2) DO NOTHING --or update ON CONFLICT (col5, col6, col7) DO NOTHING --or update This

问题 There is a constraint violation handling "On conflict" statement, working fine if i want to check 1 (!) constraint For example : INSERT INTO my_table (co1,col2..colN) VALUES (...) ON CONFLICT (col1, col2) DO NOTHING --or update But if i have 2 constaints unique(col1,col2) and unique(col5,col6,col7) , the query below is not working : INSERT INTO my_table (co1,col2..colN) VALUES (...) ON CONFLICT (col1, col2) DO NOTHING --or update ON CONFLICT (col5, col6, col7) DO NOTHING --or update This

问题 Summary: I'm getting very slow queries using few queries and annotate vs. two queries extra per item when counting related objects. Database is PostgreSQL 9.3.5. I have a model that looks something like this: class Collection(models.Model): have = models.ManyToManyField(Item, related_name='item_have', through='Have') want = models.ManyToManyField(Item, related_name='item_want', through='Want') added = models.DateTimeField() class Meta: ordering = ['-last_bump'] class Have(models.Model): item

问题 Summary: I'm getting very slow queries using few queries and annotate vs. two queries extra per item when counting related objects. Database is PostgreSQL 9.3.5. I have a model that looks something like this: class Collection(models.Model): have = models.ManyToManyField(Item, related_name='item_have', through='Have') want = models.ManyToManyField(Item, related_name='item_want', through='Want') added = models.DateTimeField() class Meta: ordering = ['-last_bump'] class Have(models.Model): item