conn.execute("create table s1_1 using s1 tags ('{\"k1\": \"v1\"}')")
```
Query JSON tag and table name from a stable.
```python
tags=conn.query("select info, tbname from s1").fetch_all_into_dict()
tags
```
The `tags` value is:
```python
[{'info':'{"k1":"v1"}','tbname':'s1_1'}]
```
To get value from JSON tag by key:
```python
k1=conn.query("select info->'k1' as k1 from s1").fetch_all_into_dict()
"""
>>> k1
[{'k1': '"v1"'}]
"""
```
Refer to [JSON type instructions](https://www.taosdata.com/en/documentation/taos-sql) for more usage of JSON type.
#### Using nanosecond in Python connector
#### Using nanosecond in Python connector
So far Python still does not completely support nanosecond type. Please refer to the link 1 and 2. The implementation of the python connector is to return an integer number for nanosecond value rather than datatime type as what ms and us do. The developer needs to handle it themselves. We recommend using pandas to_datetime() function. If Python officially support nanosecond in the future, TAOS Data might be possible to change the interface accordingly, which mean the application need change too.
So far Python still does not completely support nanosecond type. Please refer to the link 1 and 2. The implementation of the python connector is to return an integer number for nanosecond value rather than datatime type as what ms and us do. The developer needs to handle it themselves. We recommend using pandas to_datetime() function. If Python officially support nanosecond in the future, TAOS Data might be possible to change the interface accordingly, which mean the application need change too.
@@ -60,6 +60,7 @@ In TDengine, the following 10 data types can be used in data model of an ordinar
...
@@ -60,6 +60,7 @@ In TDengine, the following 10 data types can be used in data model of an ordinar
1. TDengine is case-insensitive to English characters in SQL statements and automatically converts them to lowercase for execution. Therefore, the user's case-sensitive strings and passwords need to be enclosed in single quotation marks.
1. TDengine is case-insensitive to English characters in SQL statements and automatically converts them to lowercase for execution. Therefore, the user's case-sensitive strings and passwords need to be enclosed in single quotation marks.
2. Avoid using BINARY type to save non-ASCII type strings, which will easily lead to errors such as garbled data. The correct way is to use NCHAR type to save Chinese characters.
2. Avoid using BINARY type to save non-ASCII type strings, which will easily lead to errors such as garbled data. The correct way is to use NCHAR type to save Chinese characters.
3. The numerical values in SQL statements are treated as floating or integer numbers, depends on if the value contains decimal point or is in scientific notation format. Therefore, caution is needed since overflow might happen for corresponding data types. E.g., 9999999999999999999 is overflowed as the number is greater than the largest integer number. However, 9999999999999999999.0 is treated as a valid floating number.
Json tag test case, include create table with json tag,
Json tag test case, include create table with json tag, select json tag and query with json tag in where condition, besides, include json tag in group by/order by/join/subquery.
select json tag and query with json tag in where condition,
case1: [TD-12452] fix error if json tag is NULL
besides, include json tag in group by/order by/join/subquery.
case2: [TD-12389] describe child table, tag length error if the tag is json tag
'''
'''
return
return
...
@@ -515,6 +515,23 @@ class TDTestCase:
...
@@ -515,6 +515,23 @@ class TDTestCase:
tdSql.query("select jtag->'tag3' from jsons1_16")
tdSql.query("select jtag->'tag3' from jsons1_16")
tdSql.checkData(0,0,'-2.111000000')
tdSql.checkData(0,0,'-2.111000000')
# test TD-12452
tdSql.execute("ALTER TABLE jsons1_1 SET TAG jtag=NULL")
tdSql.query("select jtag from jsons1_1")
tdSql.checkData(0,0,None)
tdSql.execute("CREATE TABLE if not exists jsons1_20 using jsons1 tags(NULL)")
tdSql.query("select jtag from jsons1_20")
tdSql.checkData(0,0,None)
tdSql.execute("insert into jsons1_21 using jsons1 tags(NULL) values(1591061628000, 11, false, '你就会','')")
