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In SQL the UNION clause combines the results of two SQL queries into a single table of all matching rows. The two queries must result in the same number of columns and compatible data types in order to unite. Any duplicate records are automatically removed unless UNION ALL is used.
In a database, a table is a collection of related data organized in table format; consisting of columns and rows. In relational databases, and flat file databases, a table is a set of data elements (values) using a model of vertical columns (identifiable by name) and horizontal rows, the cell being the unit where a row and column intersect. [1]
Supported Database Platforms Supported OSs Standalone or bundled into a larger toolkit Launch Date Astah: Change Vision: Enterprises Proprietary: MySQL, Oracle, Windows, macOS, Linux Standalone 2006 Database Workbench: Upscene Productions SMBs and enterprises Proprietary: MS SQL Server, MySQL, Oracle, Firebird, InterBase, SQL Anywhere, NexusDB ...
An SQL schema is simply a namespace within a database; things within this namespace are addressed using the member operator dot ". This seems to be a universal among all of the implementations. A true fully (database, schema, and table) qualified query is exemplified as such: SELECT * FROM database . schema . table
The reasons for this are two-fold: First, data deduplication requires overhead to discover and remove the duplicate data. In primary storage systems, this overhead may impact performance. The second reason why deduplication is applied to secondary data, is that secondary data tends to have more duplicate data.
Compare Import Export Debugger Source control Spatial Visualization Adminer: Yes Yes Yes SQL script, CSV, TSV or the above in zip (as a plugin); imports of server-site file in SQL or SQL in zip, gzip or bzip2: SQL script, CSV, TSV or the above in zip, gzip, bzip2; XML (as a plugin) No Git: Altova DatabaseSpy: No No Yes CSV, XML
Comma-separated values (CSV) is a text file format that uses commas to separate values, and newlines to separate records. A CSV file stores tabular data (numbers and text) in plain text, where each line of the file typically represents one data record.
E. F. Codd mentioned nulls as a method of representing missing data in the relational model in a 1975 paper in the FDT Bulletin of ACM-SIGMOD.Codd's paper that is most commonly cited with the semantics of Null (as adopted in SQL) is his 1979 paper in the ACM Transactions on Database Systems, in which he also introduced his Relational Model/Tasmania, although much of the other proposals from ...