FAQ Portal
Categories
Search
About
Contacts
UK
RU
EN
Home
Technology
Programming
SQL and databases
SQL and databases
100 questions
How to optimize queries?
•
EXPLAIN.
•
Indexes.
•
Avoid SELECT *.
•
LIMIT.
•
No functions on indexes.
Types of JOINs?
•
INNER.
•
LEFT.
•
RIGHT.
•
FULL OUTER.
•
CROSS.
Transactions?
•
BEGIN.
•
COMMIT.
•
ROLLBACK.
•
ACID.
•
Isolation levels.
SQL injections?
•
Prepared statements.
•
Parameterization.
•
Do not concatenate.
•
ORM.
•
Validation.
PostgreSQL vs MySQL?
•
PG: complex queries.
•
MySQL: simple CRUD.
•
PG is stricter.
•
MySQL reads faster.
•
Both production-ready.
SQL and databases: how to design schema and normalize tables?
Regarding «SQL and databases», start with reproducibility: minimal example, version, steps. This is half of debugging.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
Practice for "SQL and Databases": write a test/check that breaks, then fix the code. This way you don't "treat symptoms".
SQL and Databases: How to perform migrations and version the schema?
Answer on "SQL and Databases": read the documentation and errors thoroughly. An error message almost always indicates what is wrong.
SQL and Databases: How to set up backups and recovery?
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guesswork.
SQL and Databases: Question №10
If the question is about "SQL and Databases", start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: How to design a schema and normalize tables?
For "SQL and Databases" keep the code simple: small functions, clear names, one level of abstraction. This reduces the number of bugs.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
On the topic of "SQL and Databases" start with reproducibility: minimal example, version, steps. This is half of debugging.
SQL and Databases: How to perform migrations and version the schema?
Practice for "SQL and Databases": write a test/check that breaks, then fix the code. This way you don't "treat symptoms".
SQL and Databases: How to set up backups and recovery?
Answer on "SQL and Databases": read the documentation and errors thoroughly. An error message almost always indicates what is wrong.
SQL and Databases: Question №15
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guesswork.
SQL and Databases: How to design a schema and normalize tables?
If the question is about "SQL and Databases", start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
Keep the code simple on 'SQL and Databases': small functions, understandable names, one level of abstraction. This reduces the number of bugs.
SQL and Databases: How to perform migrations and version the schema?
Start with reproducibility on the topic 'SQL and Databases': minimal example, version, steps. This is half of debugging.
SQL and Databases: How to set up backups and recovery?
Practice for 'SQL and Databases': write a test/check that breaks, then fix the code. This way, you don't 'treat symptoms'.
SQL and Databases: Question №20
Answer on 'SQL and Databases': read the documentation and errors in full. The error message almost always indicates what is wrong.
SQL and Databases: How to design a schema and normalize tables?
For 'SQL and Databases': logging, profiling, and working with metrics are useful. Optimization without measurements is guesswork.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
If the question is about 'SQL and Databases', start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: How to perform migrations and version the schema?
Keep the code simple on 'SQL and Databases': small functions, understandable names, one level of abstraction. This reduces bugs.
SQL and Databases: How to set up backups and recovery?
Start with reproducibility on the topic 'SQL and Databases': minimal example, version, steps. This is half of debugging.
SQL and Databases: Question №25
Practice for 'SQL and Databases': write a test/check that breaks, then fix the code. This way, you don't 'treat symptoms'.
SQL and Databases: How to design a schema and normalize tables?
Answer on 'SQL and Databases': read the documentation and errors in full. The error message almost always indicates what is wrong.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guessing.
SQL and Databases: How to perform migrations and version the schema?
If the question is about "SQL and Databases", start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: How to set up backups and recovery?
For "SQL and Databases" keep the code simple: small functions, clear names, one level of abstraction. This reduces the number of bugs.
SQL and Databases: Question №30
On the topic of "SQL and Databases" start with reproducibility: minimal example, version, steps. This is half of debugging.
SQL and Databases: How to design a schema and normalize tables?
Practice for "SQL and Databases": write a test/check that breaks, then fix the code. This way you don't "treat the symptoms".
SQL and Databases: How to choose indexes and read EXPLAIN plans?
Answer on "SQL and Databases": read the documentation and errors completely. The error message almost always indicates what is wrong.
SQL and Databases: How to perform migrations and version the schema?
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guessing.
SQL and Databases: How to set up backups and recovery?
If the question is about "SQL and Databases", start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: Question №35
On the topic of "SQL and Databases" keep the code simple: small functions, clear names, one level of abstraction. This reduces the number of bugs.
SQL and Databases: How to design a schema and normalize tables?
On the topic of "SQL and Databases" start with reproducibility: minimal example, version, steps. This is half of debugging.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
Practice for "SQL and Databases": write a test/check that breaks, then fix the code. This way you don't "treat symptoms".
SQL and Databases: How to perform migrations and version the schema?
Answer on "SQL and Databases": read the documentation and errors thoroughly. An error message almost always indicates what is wrong.
SQL and Databases: How to set up backups and recovery?
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guesswork.
SQL and Databases: Question №40
If the question is about "SQL and Databases", start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: How to design a schema and normalize tables?
For "SQL and Databases" keep the code simple: small functions, clear names, one level of abstraction. This reduces bugs.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
On the topic of "SQL and Databases" start with reproducibility: minimal example, version, steps. This is half of debugging.
SQL and Databases: How to perform migrations and version the schema?
Practice for "SQL and Databases": write a test/check that breaks, then fix the code. This way you don't "treat symptoms".
SQL and Databases: How to set up backups and recovery?
Answer on "SQL and Databases": read the documentation and errors thoroughly. An error message almost always indicates what is wrong.
SQL and Databases: Question №45
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guesswork.
SQL and Databases: How to design a schema and normalize tables?
If the question is about "SQL and Databases", start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
Keep your code simple on 'SQL and Databases': small functions, understandable names, one level of abstraction. This reduces the number of bugs.
SQL and Databases: How to perform migrations and version the schema?
Start with reproducibility on the topic 'SQL and Databases': minimal example, version, steps. This is half of debugging.
SQL and Databases: How to set up backups and recovery?
Practice for 'SQL and Databases': write a test/check that breaks, then fix the code. This way you don't 'treat symptoms'.
SQL and Databases: Question №50
Answer on 'SQL and Databases': read the documentation and errors in full. The error message almost always indicates what is wrong.
SQL and Databases: How to design a schema and normalize tables?
For 'SQL and Databases': logging, profiling, and working with metrics are useful. Optimization without measurements is guesswork.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
If the question is about 'SQL and Databases', start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: How to perform migrations and version the schema?
Keep your code simple on 'SQL and Databases': small functions, understandable names, one level of abstraction. This reduces the number of bugs.
SQL and Databases: How to set up backups and recovery?
Start with reproducibility on the topic 'SQL and Databases': minimal example, version, steps. This is half of debugging.
SQL and Databases: Question №55
Practice for 'SQL and Databases': write a test/check that breaks, then fix the code. This way you don't 'treat symptoms'.
SQL and Databases: How to design a schema and normalize tables?
Answer on 'SQL and Databases': read the documentation and errors in full. The error message almost always indicates what is wrong.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guesswork.
SQL and Databases: How to perform migrations and version the schema?
If the question is about "SQL and Databases," start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: How to set up backups and recovery?
For "SQL and Databases," keep your code simple: small functions, understandable names, one level of abstraction. This reduces bugs.
SQL and Databases: question №60
On the topic of "SQL and Databases," start with reproducibility: minimal example, version, steps. This is half of debugging.
SQL and Databases: How to design a schema and normalize tables?
Practice for "SQL and Databases": write a test/check that breaks, then fix the code. This way you don't "treat symptoms".
SQL and Databases: How to choose indexes and read EXPLAIN plans?
Answer on "SQL and Databases": read the documentation and errors thoroughly. The error message almost always indicates what is wrong.
SQL and Databases: How to perform migrations and version the schema?
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guesswork.
SQL and Databases: How to set up backups and recovery?
If the question is about "SQL and Databases," start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: question №65
On the topic of "SQL and Databases," keep your code simple: small functions, understandable names, one level of abstraction. This reduces bugs.
SQL and Databases: How to design a schema and normalize tables?
On the topic of "SQL and Databases," start with reproducibility: minimal example, version, steps. This is half of debugging.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
Practice for "SQL and Databases": write a test/check that breaks, then fix the code. This way you don't "treat symptoms".
SQL and Databases: How to perform migrations and version the schema?
Answer for "SQL and Databases": read the documentation and errors thoroughly. An error message almost always indicates what is wrong.
SQL and Databases: How to set up backups and recovery?
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guesswork.
SQL and Databases: Question №70
If the question is about "SQL and Databases", start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: How to design a schema and normalize tables?
For "SQL and Databases" keep the code simple: small functions, clear names, one level of abstraction. This reduces the number of bugs.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
On the topic of "SQL and Databases" start with reproducibility: minimal example, version, steps. This is half of debugging.
SQL and Databases: How to perform migrations and version the schema?
Practice for "SQL and Databases": write a test/check that breaks, then fix the code. This way you don't "treat symptoms".
SQL and Databases: How to set up backups and recovery?
Answer for "SQL and Databases": read the documentation and errors thoroughly. An error message almost always indicates what is wrong.
SQL and Databases: Question №75
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guesswork.
SQL and Databases: How to design a schema and normalize tables?
If the question is about "SQL and Databases", start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
Keep the code simple on 'SQL and Databases': small functions, understandable names, one level of abstraction. This reduces the number of bugs.
SQL and Databases: How to perform migrations and version the schema?
Start with reproducibility on the topic 'SQL and Databases': minimal example, version, steps. This is half the debugging.
SQL and Databases: How to set up backups and recovery?
Practice for 'SQL and Databases': write a test/check that breaks, then fix the code. This way you don't 'treat symptoms'.
SQL and Databases: Question №80
Answer on 'SQL and Databases': read the documentation and errors in full. The error message almost always indicates what is wrong.
SQL and Databases: How to design a schema and normalize tables?
For 'SQL and Databases': logging, profiling, and working with metrics are useful. Optimization without measurements is guesswork.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
If the question is about 'SQL and Databases', start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: How to perform migrations and version the schema?
Keep the code simple on 'SQL and Databases': small functions, understandable names, one level of abstraction. This reduces the number of bugs.
SQL and Databases: How to set up backups and recovery?
Start with reproducibility on the topic 'SQL and Databases': minimal example, version, steps. This is half the debugging.
SQL and Databases: Question №85
Practice for 'SQL and Databases': write a test/check that breaks, then fix the code. This way you don't 'treat symptoms'.
SQL and Databases: How to design a schema and normalize tables?
Answer on 'SQL and Databases': read the documentation and errors in full. The error message almost always indicates what is wrong.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guesswork.
SQL and Databases: How to perform migrations and version the schema?
If the question is about "SQL and Databases," start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: How to set up backups and recovery?
For "SQL and Databases" keep the code simple: small functions, understandable names, one level of abstraction. This reduces the number of bugs.
SQL and Databases: Question №90
On the topic of "SQL and Databases," start with reproducibility: minimal example, version, steps. This is half of debugging.
SQL and Databases: How to design a schema and normalize tables?
Practice for "SQL and Databases": write a test/check that breaks, then fix the code. This way you don't "treat symptoms".
SQL and Databases: How to choose indexes and read EXPLAIN plans?
Answer on "SQL and Databases": read the documentation and errors thoroughly. The error message almost always indicates what is wrong.
SQL and Databases: How to perform migrations and version the schema?
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guesswork.
SQL and Databases: How to set up backups and recovery?
If the question is about "SQL and Databases," start with simple reasons: data types, null/undefined, dependencies, environment, access rights.
SQL and Databases: Question №95
On the topic of "SQL and Databases," keep the code simple: small functions, understandable names, one level of abstraction. This reduces the number of bugs.
SQL and Databases: How to design a schema and normalize tables?
On the topic of "SQL and Databases," start with reproducibility: minimal example, version, steps. This is half of debugging.
SQL and Databases: How to choose indexes and read EXPLAIN plans?
Practice for "SQL and Databases": write a test/check that breaks, then fix the code. This way you don't "treat the symptoms".
SQL and Databases: How to perform migrations and version the schema?
Answer for "SQL and Databases": read the documentation and errors thoroughly. An error message almost always indicates what is wrong.
SQL and Databases: How to set up backups and recovery?
For "SQL and Databases" it is useful: logging, profiling, and working with metrics. Optimization without measurements is guesswork.
SQL and Databases: Question №100
If the question is about "SQL and Databases", start with simple reasons: data types, null/undefined, dependencies, environment, access rights.