8 questions from the last 7 days
4
votes
1
answer
99
views
Update table 1 columns based on whether the column name exists as a value in another table
I'm trying to figure out an efficient way to do this, preferably as a single MySQL query. I have two tables that look approximately like this (I simplified it as best I could):
table1
CREATE TABLE `...
- 45
3
votes
1
answer
182
views
How to recursively inject WHERE clauses into deep subqueries and nested expressions?
I am building a SQL interceptor in Java to implement multi-tenant isolation. My goal is to parse incoming SQL statements using JSqlParser and inject a mandatory predicate tenant_id = '123' into every ...
1
vote
2
answers
12
views
Using subquery as a derived table
I am doing a SQL course and I can't figure out the solution to this question.
In a Car database, there is a Sale table with columns:
SaleID, CarID, CustomerID, LocationID, SalesRepID, SaleAmount, ...
- 11
Advice
0
votes
4
replies
93
views
Best database book for 10-thousand-foot flyer?
I'm grokking data analytics as part of the Google DA course, and I realize I'm going to need a bit more about databases than the course teaches.
Any ideas for a great introductory database book? I'm ...
0
votes
1
answer
100
views
How to optimize SELECT * queries on wide tables?
I'm a MySQL DBA moving to PolarDB IMCI. I know we can force columnstore queries like:
SELECT /*+ SET_VAR(cost_threshold_for_imci=0) */ COUNT(*) FROM t1 WHERE a > 1;
or disable them:
SELECT /*+ ...
- 47
Advice
0
votes
2
replies
120
views
Migrating data to a new database -> On-Prem or Cloud?
At my company, we're starting our data department. Currently, all the information is managed in Google Drive, and knowing this isn't ideal, I want to begin migrating the data to a database. Since we ...
- 49
0
votes
1
answer
76
views
How to use an incremental DELETE+INSERT without unique_key?
I just started a new position in a company, and they're asking me to migrate their old SQL queries to DBT, the problem is that I'm trying to do a DELETE+INSERT on a range of dates without a unique_key ...
-1
votes
0
answers
82
views
Access lookup using another column value [closed]
I have 4 tables in a MS Access database, namely
Table1 (values - A, B, C, D)
Table2 (values - P, Q, R, S)
Flags (values - Y, N)
Table3 has two columns, TYPE and DESCRIPTION
The TYPE column is a ...
