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Is there a typical state machine implementation pattern?
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I prefer to use a table driven approach for most state machines:
typedef enum { STATE_INITIAL, STATE_FOO, STATE_BAR, NUM_STATES } state_t;
typedef struct instance_data instance_data_t;
typedef state_t state_func_t( instance_data_t *data );
s...
What is a stored procedure?
...ut the user will not need to have read/write permissions on the underlying tables. This is a good first step against SQL injection.
Stored procedures do come with downsides, basically the maintenance associated with your basic CRUD operation. Let's say for each table you have an Insert, Update, Del...
Create code first, many to many, with additional fields in association table
... not possible to create a many-to-many relationship with a customized join table. In a many-to-many relationship EF manages the join table internally and hidden. It's a table without an Entity class in your model. To work with such a join table with additional properties you will have to create actu...
How to prepend a string to a column value in MySQL?
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UPDATE tablename SET fieldname = CONCAT("test", fieldname) [WHERE ...]
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Select count(*) from multiple tables
How can I select count(*) from two different tables (call them tab1 and tab2 ) having as result:
18 Answers
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How to deal with page breaks when printing a large HTML table
I have a project which requires printing an HTML table with many rows.
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Is C++14 adding new keywords to C++?
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Table 4 (Keywords) in N3936 (C++14):
alignas continue friend register true
alignof decltype goto reinterpret_cast try
asm default ...
Why use multiple columns as primary keys (composite primary key)
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Another example of compound primary keys are the usage of Association tables. Suppose you have a person table that contains a set of people and a group table that contains a set of groups. Now you want to create a many to many relationship on person and group. Meaning each person can belong t...
how to emulate “insert ignore” and “on duplicate key update” (sql merge) with postgresql?
...meant that you use a query like this: "start transaction; create temporary table temporary_table as select * from test where false; copy temporary_table from 'data_file.csv'; lock table test; update test set data=temporary_table.data from temporary_table where test.id=temporary_table.id; insert into...
Find most frequent value in SQL column
How can I find the most frequent value in a given column in an SQL table?
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