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45 lines
1.8 KiB
Markdown
45 lines
1.8 KiB
Markdown
---
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sidebar_position: 46
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sidebar_label: input
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---
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# input {#input}
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`input(structure)` - table function that allows effectively convert and insert data sent to the
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server with given structure to the table with another structure.
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`structure` - structure of data sent to the server in following format `'column1_name column1_type, column2_name column2_type, ...'`.
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For example, `'id UInt32, name String'`.
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This function can be used only in `INSERT SELECT` query and only once but otherwise behaves like ordinary table function
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(for example, it can be used in subquery, etc.).
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Data can be sent in any way like for ordinary `INSERT` query and passed in any available [format](../../interfaces/formats.md#formats)
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that must be specified in the end of query (unlike ordinary `INSERT SELECT`).
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The main feature of this function is that when server receives data from client it simultaneously converts it
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according to the list of expressions in the `SELECT` clause and inserts into the target table. Temporary table
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with all transferred data is not created.
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**Examples**
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- Let the `test` table has the following structure `(a String, b String)`
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and data in `data.csv` has a different structure `(col1 String, col2 Date, col3 Int32)`. Query for insert
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data from the `data.csv` into the `test` table with simultaneous conversion looks like this:
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<!-- -->
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``` bash
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$ cat data.csv | clickhouse-client --query="INSERT INTO test SELECT lower(col1), col3 * col3 FROM input('col1 String, col2 Date, col3 Int32') FORMAT CSV";
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```
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- If `data.csv` contains data of the same structure `test_structure` as the table `test` then these two queries are equal:
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<!-- -->
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``` bash
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$ cat data.csv | clickhouse-client --query="INSERT INTO test FORMAT CSV"
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$ cat data.csv | clickhouse-client --query="INSERT INTO test SELECT * FROM input('test_structure') FORMAT CSV"
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```
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