Managing Hierarchical Data in MySQL

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Mysql – Having

As per SQL standard - The HAVING clause without a GROUP BY clause acts like the WHERE clause. If the HAVING clause contains no aggregate functions, use the WHERE clause for faster performance. SO Link here's an example of a SQL statement where we use HAVING: select column1 from table1 where condition1 having condition2; isn't it the same exact thing if we do this: select column1 from… Continue reading Mysql – Having

Mysql Like Query

Link B-Tree Index Characteristics   A B-tree index can be used for column comparisons in expressions that use the =, >, >=, <, <=, or BETWEEN operators. The index also can be used for LIKE comparisons if the argument to LIKE is a constant string that does not start with a wildcard character. For example, the following SELECT statements use indexes: SELECT * FROM tbl_name WHERE key_col LIKE… Continue reading Mysql Like Query

Schema vs Database

Depends on the database server. MySQL doesn't care, its basically the same thing. In MySQL, physically, a schema is synonymous with a database. You can substitute the keyword SCHEMA instead of DATABASE in MySQL SQL syntax, for example using CREATE SCHEMA instead of CREATE DATABASE. Some other database products draw a distinction. For example, in… Continue reading Schema vs Database