Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!
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比如在 LEFT JOIN 中过滤条件写在 ON 和 WHERE 的区别。
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Table-value function 和 scalar-valued function 的区别.
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char、varchar、nvarchar之间的区别(包括 …
General Tips on SQL
Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!
Performance
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Avoid implicit data convertion! This might cause full table scan which hurts performance badly. For more discussions, please refer to 一条垃圾SQL，把 64 核 CPU 快 …
Data Types in Different Programming Languages
Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!
| Data Type | C | C++ | Rust | Java | Python | numpy | pyarrow | Spark SQL | SQL |
|---|---|---|---|---|---|---|---|---|---|
| 8 bit integer | short (16-bit) | int8_t | i8 | short (16-bit) | int (arbitrary precision) | int8 | TinyInt … |
Access Control in Spark SQL
Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!
Grant Permission to Users
GRANT
priv_type [, priv_type ] ...
ON database_table_or_view_name
TO principal_specification [, principal_specification] ...
[WITH GRANT OPTION];
Examples:
GRANT SELECT ON table1 TO USER user1;
GRANT SELECT ON DATABASE db1 TO USER user1 …SQL Translation Tools
Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!
The ORM library SQLAlchemy
can be leverage
SQL Translation Tools
Use Column Alias in SQL
Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!
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Logically any
SELECTis processed in following order:- from
- where
- group by
- having
- olap functions
- qualify
- select
- sample
- order by
Besides the proprietary
QUALIFY/SAMPLEevery DBMS will do it exactly …