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Databases
Published in David Austerberry, Digital Asset Management, 2012
The data manipulation language (DML) is used to access and manipulate records, specifically to select, insert, update, and delete records. The select statement is used to perform queries. A query results in a temporary table called a view, which forms a subset of the information stored within one or more tables. For example, you could return all the spot titles on a given tape number.
Database querying using SQL
Published in Benjamin S. Baumer, Daniel T. Kaplan, Nicholas J. Horton, Modern Data Science with R, 2021
Benjamin S. Baumer, Daniel T. Kaplan, Nicholas J. Horton
Next, we want to build a query. Queries in SQL start with the SELECT keyword and consist of several clauses, which have to be written in this order: SELECT allows you to list the columns, or functions operating on columns, that you want to retrieve. This is an analogous operation to the select() verb in dplyr, potentially combined with mutate().FROM specifies the table where the data are.JOIN allows you to stitch together two or more tables using a key. This is analogous to the inner_join() and left_join() commands in dplyr.WHERE allows you to filter the records according to some criteria. This is an analogous operation to the filter() verb in dplyr.GROUP BY allows you to aggregate the records according to some shared value. This is an analogous operation to the group_by() verb in dplyr.HAVING is like a WHERE clause that operates on the result set—not the records themselves. This is analogous to applying a second filter() command in dplyr, after the rows have already been aggregated.ORDER BY is exactly what it sounds like—it specifies a condition for ordering the rows of the result set. This is analogous to the arrange() verb in dplyr.LIMIT restricts the number of rows in the output. This is similar to the R commands head() and slice().
BAMN: a modeling method for business activity monitoring systems
Published in Journal of Decision Systems, 2019
Christian Janiesch, Martin Matzner
EPL uses SELECT, FROM, WHERE, GROUP BY, HAVING and ORDER BY clauses to query event streams in a similar fashion of SQL accessing tables of a database. INSERT INTO is used to specify output event streams and PATTERN as well as OUTPUT clauses to cater for other CEP specific operations. The following code segment shows the definition of an expression, which adds two basic measures and outputs all of them, which exceed the value of 500 in another event stream for further analyses. It corresponds to a composed basic measure with a minimum threshold deviation range for a target definition (cf. Figure 4).
Interactive Visual Exploration of Big Relational Datasets
Published in International Journal of Human–Computer Interaction, 2023
Katerina Vitsaxaki, Stavroula Ntoa, George Margetis, Nicolas Spyratos
An important note is in order here. In this paper, we focus on analytic queries that are triples of well-formed functional expressions. As we have seen, the user defines an analytic query through a sequence of clicks over his context and such a query is then translated to an SQL Group-by query on the underlying database. However, our interface allows also expressing simple queries as well. Recall that a simple query over a context C is just a single functional expression whose operands are edges of C and whose operations are from the functional algebra. Simple queries correspond to relational algebra expressions, which in turn can be translated as SQL queries of the type Select-From-Where.
A metaprotocol-based Internet of Things architecture
Published in Automatika, 2022
L. Milić, L. Jelenković, I. Magdalenić
A retrieval of data from a node is requested by a SELECT message. The SQL SELECT query can be a simple query such as “SELECT col1, col2 FROM table;” or more complex with aliases, a WHERE, and other clauses and conditions. When data is requested from a sensor node, the query can be even simpler, e.g. “SELECT val1, val2;”, or “SELECT *;” – or even “X1*” when encoded.