12/27/2023 0 Comments Android sqlite order by numbersIn case there is an integer overflow error happens and all input values are NULL or integers, the SUM function throws an integer overflow exception. The result of the SUM function is NULL if and only if all input values are NULL. If any input value is neither an integer nor a NULL value, the result of the SUM function is a floating-point value. The result of the SUM function is an integer if all input non-NULL values are integers. If you want to calculate the sum of unique values, you have to specify the DISTINCT clause explicitly in the expression. It means that all the input values, whether duplicate or not, are considered when the SUM function performs the calculation. The SUM function uses ALL clause by default. The following expression illustrates the syntax of the SUM function: SUM( expression) Code language: SQL (Structured Query Language) ( sql ) The SUM function is an aggregate function that returns the sum the non-NULL values or only the distinct values in a group. > timeit.Timer(cast_affinity, setup).timeit(number = 1)Īs we can see its a bit slower though not by much, interesting.Summary: in this tutorial, you will learn how to use the SQLite SUM function to calculate the sum of all values. > timeit.Timer(cast_conv, setup).timeit(number = 1) > cast_affinity = "result = c.execute('SELECT * FROM T ORDER BY (value + 0)')" > cast_conv = "result = c.execute('SELECT * FROM T ORDER BY CAST(value AS INTEGER)')" _ = c.execute('INSERT INTO T (value) VALUES (%i)' % index) I was curios so I ran some benchmarks: > setup = """ An operand on a mathematical operator that does not look in any way numeric and is not NULL is converted to 0 or 0.0. A NULL operand on a mathematical operator yields a NULL result. The cast is carried through even if it is lossy and irreversible. Application of a CAST expression is different to application of a column affinity, as with a CAST expression the storage class conversion is forced even if it is lossy and irrreversible.Īll mathematical operators (+, -, *, /, %, >, &, and |) cast both operands to the NUMERIC storage class prior to being carried out. Well thats interesting, though I dont know how many DBMS support such an operation so I don't recommend it just in case you ever need to use a different system that doesn't support it, not to mention you are adding an extra operation, which can affect performance, though you also do this ORDER BY (field + 0) Im going to investigate the performanceĪ CAST expression is used to convert the value of to a different storage class in a similar way to the conversion that takes place when a column affinity is applied to a value. Is the a way to "officially" convert it like C's atoi? If I do this: ".ORDER BY (field+1)" I can workaround this, because somehow the string is internally being converted to integer. Sqlite> SELECT * FROM T ORDER BY CAST(value AS INTEGER) Sqlite> INSERT INTO T (value) VALUES ('03') Sqlite> INSERT INTO T (value) VALUES ('02') Sqlite> INSERT INTO T (value) VALUES ('01') Sqlite> INSERT INTO T (value) VALUES ('12') Sqlite> INSERT INTO T (value) VALUES ('11') Sqlite> INSERT INTO T (value) VALUES ('10') sqlite> CREATE TABLE T (value VARCHAR(2)) You can use CAST to cast the expression to an Integer.
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