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What's the difference between @JoinColumn and mappedBy when using a JPA @OneToMany association
...t this entity is the owner of the relationship (that is: the corresponding table has a column with a foreign key to the referenced table), whereas the attribute mappedBy indicates that the entity in this side is the inverse of the relationship, and the owner resides in the "other" entity. This also ...
Fastest Way to Find Distance Between Two Lat/Long Points
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Create your points using Point values of Geometry data types in MyISAM table. As of Mysql 5.7.5, InnoDB tables now also support SPATIAL indices.
Create a SPATIAL index on these points
Use MBRContains() to find the values:
SELECT *
FROM table
WHERE MBRContains(LineFromText(CONCAT(
...
Dynamic Sorting within SQL Stored Procedures
...
This approach keeps the sortable columns from being duplicated twice in the order by, and is a little more readable IMO:
SELECT
s.*
FROM
(SELECT
CASE @SortCol1
WHEN 'Foo' THEN t.Foo
WHEN 'Bar' THEN t.Bar
ELSE null
END as ...
SQL Server 2005 How Create a Unique Constraint?
How do I create a unique constraint on an existing table in SQL Server 2005?
10 Answers
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Quick Way to Implement Dictionary in C
...ection 6.6 of The C Programming Language presents a simple dictionary (hashtable) data structure. I don't think a useful dictionary implementation could get any simpler than this. For your convenience, I reproduce the code here.
struct nlist { /* table entry: */
struct nlist *next; /* next ent...
“’” showing on page instead of “ ' ”
...h is being decoded as CP-1252 instead of UTF-8. If you check the encodings table, then you see that this character is in UTF-8 composed of bytes 0xE2, 0x80 and 0x99. If you check the CP-1252 code page layout, then you'll see that each of those bytes stand for the individual characters â, € and ...
Add unique constraint to combination of two columns
I have a table and, somehow, the same person got into my Person table twice. Right now, the primary key is just an autonumber but there are two other fields that exist that I want to force to be unique.
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How do I specify unique constraint for multiple columns in MySQL?
I have a table:
14 Answers
14
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What is dynamic programming? [closed]
...problem.
With dynamic programming, you store your results in some sort of table generally. When you need the answer to a problem, you reference the table and see if you already know what it is. If not, you use the data in your table to give yourself a stepping stone towards the answer.
The Cormen ...
Restrict varchar() column to specific values?
...t on that column which would restrict values? Something like:
CREATE TABLE SomeTable
(
Id int NOT NULL,
Frequency varchar(200),
CONSTRAINT chk_Frequency CHECK (Frequency IN ('Daily', 'Weekly', 'Monthly', 'Yearly'))
)
...