There is no “correct” name, but the academic name would be an “Associative Table” (see See the Wikipedia article Associative Entity). Other common names are (in alphabetical order): Association table Bridge table Cross-reference table Crosswalk Intermediary table Intersection table Join table Junction table Link table Linking table Many-to-many resolver Map table Mapping table Pivot Table … Read more
To insert a single row of data: INSERT INTO USERS VALUES (1, ‘Mike’, ‘Jones’); To do an insert on specific columns (as opposed to all of them) you must specify the columns you want to update. INSERT INTO USERS (FIRST_NAME, LAST_NAME) VALUES (‘Stephen’, ‘Jiang’); To insert multiple rows of data in SQL Server 2008 or … Read more
I would go with option 1. It is perfectly fine to have two foreign key columns referencing the same primary key column in a different table since each foreign key value will reference a different record in the related table. I’m sure option 2 would work, but you would essentially have a 1-to-1 relationship between … Read more
To show an example of what others have been describing: SELECT Col1, — All of the columns you want to dedupe on Col2, — which is not neccesarily all of the columns Col3, — in the table Col4, Col5, Col6, Col7, Col8, Col9, Col10 FROM MyTable GROUP BY Col1, Col2, Col3, Col4, Col5, Col6, Col7, … Read more
Every RDBMS is a DBMS, but the opposite is not true: RDBMS is a DBMS which is based on the relational model, but not every DBMS must be relational. However, since RDBMS are most common, sometimes the term DBMS is used to denote a DBMS which is NOT relational. It depends on the context.
WGS84 datum are usually given as coordinates in a fully decimal notation, usually with 5 decimal places, so for latitude (-90 to +90) you could use decimal(7, 5) (-90.00000 to 90.00000), for longitude you could use decimal(8, 5) (-180.00000 to 180.00000). .00001 gives an precision of around a meter at the equator The DECIMAL/NUMERIC data … Read more
It’s a matter of choice actually and this question can raise opinion based answers from my point of view. What I always do, even if it’s redundant is I create primary key on auto increment column (I call it technical key) to keep it consistent within the database, allow for “primary key” to change in … Read more
You can do this from SQL Server 2008 onwards using a table value constructor. SELECT * FROM ( VALUES(1, ‘red’), (2, ‘orange’), (5, ‘yellow’), (10, ‘green’), (11, ‘blue’), (12, ‘indigo’), (20, ‘violet’)) AS Colors(Id, Value) More information here: Table Value Constructor
I was looking for an answer on the same subject, about “bulk/batch” update. People often describe the problem by comparing it with insert clause with multiple value sets (the “bulk” part). INSERT INTO mytable (mykey, mytext, myint) VALUES (1, ‘text1’, 11), (2, ‘text2’, 22), … Clear answer was still avoiding me, but I found the … Read more
It is very easy to misunderstand the CAP properties, hence I’m providing some illustrations to make it easier. Consistency: A query Q will produce the same answer A regardless the node that handles the request. In order to guarantee full consistency we need to ensure that all nodes agree on the same value at all … Read more