Structured Query Language is a relatively simple language, but all can get complicated when working with data sets containing millions of records. Whether working with mid-size or large-size tables, it is critical that you know how to code top-performing SQL statements. Too much time and resources are wasted trying to fix code writing errors. To save your team time, effort, and resources, here are some common mistakes you should avoid while working on SQL query builder tool:
Lost or forgotten Primary Keys – All tables require primary keys to ensure performance. Without a primary key, your tables are not following standard SQL requirements. As a result, performance suffers. Primary keys can be automatically put in place as clustered indexes. This speeds up queries. Keys should always be unique, so to streamline generation, you may use an auto-incremented numeric value, provided that you don’t have any other column within the table that meets this unique requirement. Keys are useful in setting up relationship databases. They can be linked to foreign keys, making it easy to connect two tables together.
Unoptimized NOT IN or IN statements – While convenient, NOT IN and IN statements are not very well optimized. Instead, replace them with a JOIN statement, which will help your database return queries faster. JOIN statements join two tables using primary and foreign keys, effectively improving the speed of the query and allowing for an overall better performance.
Poor management of data redundancy – Data redundancy can be good for backups. However, they may not be as useful for table data. Tables should maintain unique data sets that don’t repeat data in any other table location. Many new SQL developers find it difficult to manage data redundancy as it is very easy to overlook normalization rules and to repeat data across different tables for convenience. This however, is unnecessary and only represents bad table design. As a rule of thumb, keep your data in a single location and use primary and foreign key relationships to facilitate data query.
Forgotten NULL and Empty String Values – There has been a decades-old debate between NULL and Empty String values and until today, database administrators and developers differ in opinion when it comes to them. Nevertheless, NULL values can be used when there is no value present, or you may also choose to use actual literal values like 0 integer values or zero-length strings. Whatever you choose, make sure that what you input within the database is uniform across all tables and queries.
About the Author:
This article is written by the CTO of Datasparc Inc. They offer DBHawk™ – a web-based database management & self-service business intelligence software designed for Oracle, SQL Server and other databases.
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About the Author
Mike Shah Joined: January 14th, 2016 Articles Posted: 15
