ch_join_query

Wraps two SQL sub-queries in a single <code>SELECT ... JOIN ... USING ...</code>
statement. Both sub-queries are used as derived tables, so they can be any
valid <code>SELECT</code> statements.

Facilitate the management of data from knowledge
resources that are frequently used alone or together
in research environments.
In 'TKCat', knowledge resources are manipulated as modeled database (MDB)
objects. These objects provide access to the data tables along with a general
description of the resource and a detailed data model documenting the
tables, their fields and their relationships.
These MDBs are then gathered in catalogs that can be easily
explored and shared.
Finally, 'TKCat' provides tools to easily subset, filter and combine MDBs and
create new catalogs suited for specific needs.

Patrice Godard

TKCat

Tailored Knowledge Catalog

ch_join_query function

<dl><dt>q1</dt>
<dd>a character string with the left-hand side <code>SELECT</code> sub-query</dd>
<dt>q2</dt>
<dd>a character string with the right-hand side <code>SELECT</code> sub-query</dd>
<dt>using</dt>
<dd>a character string with the column(s) to join on, as expected
after the <code>USING</code> keyword (e.g. <code>"id"</code> or <code>"(id, version)"</code>)</dd>
<dt>type</dt>
<dd>the join type, passed verbatim before the <code>JOIN</code> keyword
(e.g. <code>"LEFT"</code>, <code>"INNER"</code>, <code>"FULL"</code>, <code>"ANY LEFT"</code>). Default: <code>"LEFT"</code>.</dd>
<dt>select</dt>
<dd>a character string with the columns to select. Default:
<code>"*"</code>. Columns can be qualified with the sub-query aliases (see <code>a1</code>/<code>a2</code>)
to disambiguate non-key columns present on both sides.</dd>
<dt>a1</dt>
<dd>alias given to the left-hand side sub-query. Default: <code>"l"</code>.</dd>
<dt>a2</dt>
<dd>alias given to the right-hand side sub-query. Default: <code>"r"</code>.</dd></dl>

Arguments

Build a ClickHouse JOIN query from two sub-queries — ch_join_query

<dl>

<dt>q1</dt>
<dd>a character string with the left-hand side <code>SELECT</code> sub-query</dd>


<dt>q2</dt>
<dd>a character string with the right-hand side <code>SELECT</code> sub-query</dd>


<dt>using</dt>
<dd>a character string with the column(s) to join on, as expected
after the <code>USING</code> keyword (e.g. <code>"id"</code> or <code>"(id, version)"</code>)</dd>


<dt>type</dt>
<dd>the join type, passed verbatim before the <code>JOIN</code> keyword
(e.g. <code>"LEFT"</code>, <code>"INNER"</code>, <code>"FULL"</code>, <code>"ANY LEFT"</code>). Default: <code>"LEFT"</code>.</dd>


<dt>select</dt>
<dd>a character string with the columns to select. Default:
<code>"*"</code>. Columns can be qualified with the sub-query aliases (see <code>a1</code>/<code>a2</code>)
to disambiguate non-key columns present on both sides.</dd>


<dt>a1</dt>
<dd>alias given to the left-hand side sub-query. Default: <code>"l"</code>.</dd>


<dt>a2</dt>
<dd>alias given to the right-hand side sub-query. Default: <code>"r"</code>.</dd>

</dl>

ch_join_query: Build a ClickHouse `JOIN` query from two sub-queries

Description

Usage

Value

Arguments

See Also