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INNER JOIN ON vs WHERE clause
...It is generally considered more readable, especially when you join lots of tables.
It can also be easily replaced with an OUTER JOIN whenever a need arises.
The WHERE syntax is more relational model oriented.
A result of two tables JOINed is a cartesian product of the tables to which a filter is ...
Add new column with foreign key constraint in one command
...to add the column and the foreign key constraint using two separate ALTER TABLE commands:
12 Answers
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Create table in SQLite only if it doesn't exist already
I want to create a table in a SQLite database only if doesn't exist already. Is there any way to do this? I don't want to drop the table if it exists, only create it if it doesn't.
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MySQL 'create schema' and 'create database' - Is there any difference
...EATE SCHEMA" command, and it served to introduce
multiple name spaces for table and view names. All tables and views were
created within a "schema". I do not know whether that version defined
some cross-schema access to tables and views, but I assume it did.
AFAIR, no product (at least back then)...
Colspan all columns
... td tag should span all columns (when the exact amount of columns in the table will be variable/difficult to determine when the HTML is being rendered)? w3schools mentions you can use colspan="0" , but it doesn't say exactly what browsers support that value (IE 6 is in our list to support).
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Find and Replace text in the entire table using a MySQL query
...w can I run a query to find and replace a text with new text in the entire table in phpmyadmin?
13 Answers
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Count number of occurences for each unique value
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Perhaps table is what you are after?
dummyData = rep(c(1,2, 2, 2), 25)
table(dummyData)
# dummyData
# 1 2
# 25 75
## or another presentation of the same data
as.data.frame(table(dummyData))
# dummyData Freq
# 1 1 ...
MySQL case insensitive select
...in did mention collate was better) We had historical data moved into mysql table which broke legacy logic because of certain column values having insensitive case. We needed to know the difference between "GE1234" and "ge1234", they needed to be unique and stay logged that way. We set our column in ...
When to use single quotes, double quotes, and backticks in MySQL
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Backticks are to be used for table and column identifiers, but are only necessary when the identifier is a MySQL reserved keyword, or when the identifier contains whitespace characters or characters beyond a limited set (see below) It is often recommende...
Explicit vs implicit SQL joins
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Personally I prefer the join syntax as its makes it clearer that the tables are joined and how they are joined. Try compare larger SQL queries where you selecting from 8 different tables and you have lots of filtering in the where. By using join syntax you separate out the parts where the tabl...