It’s sometimes difficult to know which SQL syntax to use when combining data that spans multiple tables. SQL provides several different statements for performing this type of task; knowing which to apply will yield efficient and correct results. In this article, I’ll discuss some of the more...
Whichever method you use to compare tables, they can be hard to remember and fiddly to write. It would be easier if you could put the logic in a function. Then pass the tables and columns you want to compare to that. Enter SQL macros! These enable you to create query templates. At p...
SQL Queries Subquery SUM 1. Overview All relational databases support summing two or more table columns/fields in a single SQL query. Summing of column values is typically used for numeric data (int, decimal, float, double). The summing of column values arithmetically adds the values and ret...
As you can see, the query has obtained records fromsakila_prod.customerwhere there is no matching record in terms of bothcustomer_idandfirst_namein thesakila.customertable. Spot missing records in a source database Another way to ensure data consistency is to compare two identical tables in di...
How can we use sys.columns to see if two tables have the same schema? Consider this query: 1 2 3 4 5 6 7 8 9 SELECT * FROM sys.columns WHERE object_id = OBJECT_ID(N'Original') EXCEPT SELECT * FROM sys.columns WHERE object_id = OBJECT_ID(N'Revised'); If the two tables ...
How to get count for different columns on same table OVER Clause (Transact-SQL) Using PIVOT and UNPIVOT SUM over distinct rows with multiple joinsnear Rolling sum / count / average over date interval The long Version Following the data and definitions for each table involved in the qu...
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Add Time in SQL HH:MM:SS to another HH:MM:SS Adding a column to a large (100 million rows) table with default constraint adding a extra column in a pivot table created uisng T-SQL Pivot Table query Adding a partition scheme to an existing table. Adding a Value to a 'date' Column...
FROM information_schema.tables WHERE table_schema='[schema_name]' ORDER BY data_free DESC;Copy The query displays the name of the table, the total space, and unused allocated space. By default, the values print in bytes. Note:To display information forall databases, omit the line:WHERE tabl...
JavaScript Object Notation (JSON) is a lightweight data transfer format. It's the de facto standard for document exchange. So it's likely you'll want to send and receive JSON documents from and to your database. And store them in your tables. Oracle Dat