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# Data Type Conversion Function

The IoTDB currently supports 6 data types, including INT32, INT64 ,FLOAT, DOUBLE, BOOLEAN, TEXT. When we query or evaluate data, we may need to convert data types, such as TEXT to INT32, or FLOAT to DOUBLE. IoTDB supports cast function to convert data types.

Syntax example:

```sql
SELECT cast(s1 as INT32) from root.sg
```

The syntax of the cast function is consistent with that of PostgreSQL. The data type specified after AS indicates the target type to be converted. Currently, all six data types supported by IoTDB can be used in the cast function. The conversion rules to be followed are shown in the following table. The row represents the original data type, and the column represents the target data type to be converted into:

|             | **INT32**                                                    | **INT64**                                                    | **FLOAT**                                                    | **DOUBLE**              | **BOOLEAN**                                                  | **TEXT**                         |
| ----------- | ------------------------------------------------------------ | ------------------------------------------------------------ | ------------------------------------------------------------ | ----------------------- | ------------------------------------------------------------ | -------------------------------- |
| **INT32**   | No need to cast                                              | Cast directly                                                | Cast directly                                                | Cast directly           | !=0 : true<br />==0: false                                   | String.valueOf()                 |
| **INT64**   | Out of the range of INT32: throw Exception<br />Otherwise: Cast directly | No need to cast                                              | Cast directly                                                | Cast directly           | !=0L : true<br />==0: false                                  | String.valueOf()                 |
| **FLOAT**   | Out of the range of INT32: throw Exception<br />Otherwise: Math.round() | Out of the range of INT64: throw Exception<br />Otherwise: Math.round() | No need to cast                                              | Cast directly           | !=0.0f : true<br />==0: false                                | String.valueOf()                 |
| **DOUBLE**  | Out of the range of INT32: throw Exception<br />Otherwise: Math.round() | Out of the range of INT64: throw Exception<br />Otherwise: Math.round() | Out of the range of FLOAT：throw Exception<br />Otherwise: Cast directly | No need to cast         | !=0.0 : true<br />==0: false                                 | String.valueOf()                 |
| **BOOLEAN** | true: 1<br />false: 0                                        | true: 1L<br />false: 0                                       | true: 1.0f<br />false: 0                                     | true: 1.0<br />false: 0 | No need to cast                                              | true: "true"<br />false: "false" |
| **TEXT**    | Integer.parseInt()                                           | Long.parseLong()                                             | Float.parseFloat()                                           | Double.parseDouble()    | text.toLowerCase =="true" : true<br />text.toLowerCase =="false" : false<br />Otherwise: throw Exception | No need to cast                  |

#### Examples

```
// timeseries
IoTDB> show timeseries root.sg.d1.**
+-------------+-----+--------+--------+--------+-----------+----+----------+--------+------------------+
|   Timeseries|Alias|Database|DataType|Encoding|Compression|Tags|Attributes|Deadband|DeadbandParameters|
+-------------+-----+--------+--------+--------+-----------+----+----------+--------+------------------+
|root.sg.d1.s3| null| root.sg|   FLOAT|   PLAIN|     SNAPPY|null|      null|    null|              null|
|root.sg.d1.s4| null| root.sg|  DOUBLE|   PLAIN|     SNAPPY|null|      null|    null|              null|
|root.sg.d1.s5| null| root.sg| BOOLEAN|   PLAIN|     SNAPPY|null|      null|    null|              null|
|root.sg.d1.s6| null| root.sg|    TEXT|   PLAIN|     SNAPPY|null|      null|    null|              null|
|root.sg.d1.s1| null| root.sg|   INT32|   PLAIN|     SNAPPY|null|      null|    null|              null|
|root.sg.d1.s2| null| root.sg|   INT64|   PLAIN|     SNAPPY|null|      null|    null|              null|
+-------------+-----+--------+--------+--------+-----------+----+----------+--------+------------------+

// data of timeseries
IoTDB> select * from root.sg.d1;
+-----------------------------+-------------+-------------+-------------+-------------+-------------+-------------+
|                         Time|root.sg.d1.s3|root.sg.d1.s4|root.sg.d1.s5|root.sg.d1.s6|root.sg.d1.s1|root.sg.d1.s2|
+-----------------------------+-------------+-------------+-------------+-------------+-------------+-------------+
|1970-01-01T08:00:00.000+08:00|          0.0|          0.0|        false|        10000|            0|            0|
|1970-01-01T08:00:00.001+08:00|          1.0|          1.0|        false|            3|            1|            1|
|1970-01-01T08:00:00.002+08:00|          2.7|          2.7|         true|         TRue|            2|            2|
|1970-01-01T08:00:00.003+08:00|         3.33|         3.33|         true|        faLse|            3|            3|
+-----------------------------+-------------+-------------+-------------+-------------+-------------+-------------+

// cast BOOLEAN to other types
IoTDB> select cast(s5 as INT32), cast(s5 as INT64),cast(s5 as FLOAT),cast(s5 as DOUBLE), cast(s5 as TEXT) from root.sg.d1
+-----------------------------+----------------------------+----------------------------+----------------------------+-----------------------------+---------------------------+
|                         Time|CAST(root.sg.d1.s5 AS INT32)|CAST(root.sg.d1.s5 AS INT64)|CAST(root.sg.d1.s5 AS FLOAT)|CAST(root.sg.d1.s5 AS DOUBLE)|CAST(root.sg.d1.s5 AS TEXT)|
+-----------------------------+----------------------------+----------------------------+----------------------------+-----------------------------+---------------------------+
|1970-01-01T08:00:00.000+08:00|                           0|                           0|                         0.0|                          0.0|                      false|
|1970-01-01T08:00:00.001+08:00|                           0|                           0|                         0.0|                          0.0|                      false|
|1970-01-01T08:00:00.002+08:00|                           1|                           1|                         1.0|                          1.0|                       true|
|1970-01-01T08:00:00.003+08:00|                           1|                           1|                         1.0|                          1.0|                       true|
+-----------------------------+----------------------------+----------------------------+----------------------------+-----------------------------+---------------------------+

// cast TEXT to numeric types
IoTDB> select cast(s6 as INT32), cast(s6 as INT64), cast(s6 as FLOAT), cast(s6 as DOUBLE) from root.sg.d1 where time < 2
+-----------------------------+----------------------------+----------------------------+----------------------------+-----------------------------+
|                         Time|CAST(root.sg.d1.s6 AS INT32)|CAST(root.sg.d1.s6 AS INT64)|CAST(root.sg.d1.s6 AS FLOAT)|CAST(root.sg.d1.s6 AS DOUBLE)|
+-----------------------------+----------------------------+----------------------------+----------------------------+-----------------------------+
|1970-01-01T08:00:00.000+08:00|                       10000|                       10000|                     10000.0|                      10000.0|
|1970-01-01T08:00:00.001+08:00|                           3|                           3|                         3.0|                          3.0|
+-----------------------------+----------------------------+----------------------------+----------------------------+-----------------------------+

// cast TEXT to BOOLEAN
IoTDB> select cast(s6 as BOOLEAN) from root.sg.d1 where time >= 2
+-----------------------------+------------------------------+
|                         Time|CAST(root.sg.d1.s6 AS BOOLEAN)|
+-----------------------------+------------------------------+
|1970-01-01T08:00:00.002+08:00|                          true|
|1970-01-01T08:00:00.003+08:00|                         false|
+-----------------------------+------------------------------+
```