I am using SQLite.
In my database, I have a integer column value like 20050819. I would like to convert this as date column as like 2005-08-19.
I can achieve my requirement when using the function CONVERT(columnName, DATETIME) in MySQL server. But I need the same result in SQLite.
Is this possible in SQLite query?
You basically have to break apart the date:
select printf('%4d-%02.2d-%02.2d',
columnname/10000, columnname%10000/100, columnname%100)
from tablename;
P.S.
If you have the choice, you will be far better off storing the date in ISO standard format ('YYYY-MM-DD') in the database in the first place.
Related
In Sqlite I want to extract the date and time portions of a DateTime field separately in a view and return them also as a datetime, not strings. I've tried Cast, Date(), datetime(), but they all return strings.
I've read the SQLite documentation and understand how there is not an actual Date data type. Yet a Table field defined as DateTime is able to be parsed as a Date by an Excel query, but calculations on that field are not. I'm trying to do all data prep in the database view.
My data has the following field taken directly from the table definition:
LastModifiedDate datetime
I want the date (without time) to have the same DateTime data type as LastModifiedDate, not Text, because I use this view in many spreadsheets. I can apply Excel Date functions and formatting to LastModifiedDate field directly as returned from the ODBC query to Excel, and want to do the same to the Date-only part. I don't want to have to put a string-to-date conversion in every spreadsheet when I know it can get the date natively from Sqlite in LastModifiedDate.
SELECT LastModifiedDate,
date(LastModifiedDate) as Datepart,
cast(LastModifiedDate as numeric) as Date2
FROM Transactions
LastModifiedDate Datepart Date2
2019-07-28 18:22:38.9165394 2019-07-28 2019
LastModifiedDate in the above query is interpreted in Excel as a date to which date formats and date functions can be applied with no further processing required. Datepart above is returned as Text to Excel, and I can't apply date functions and formats without further pre-processing in Excel. I would like Datepart to be interpreted a date in Excel just as LastModifiedDate is.
I'm looking at the ch-werner.de sqliteodbc-0.9998. It will return an ODBC TIMESTAMP type only if the column decltype starts with timestamp or datetime. It returns ODBC TIME only for decltypes starting with time and ODBC DATE only for decltypes starting with date.
sqlite3 provides this decltype only for result table columns that are direct database column references. So if your SELECT statement has some expression that is more than a plain column reference, the decltype is lost. sqlite3 works like this at least up to version 3.39.0. It is documented.
The CAST expression converts the value of given expression to a storage classes by the determined affinity of the given declared type, but does not assign decltype to the result.
If you want to see the decltypes for query columns, you can use the sqlite3 cli and give it command .stats 2. Then it'll output the column declared types for each statement it executes.
If the decltype is found, the sqliteodbc-0.9998 will always parse string values into ODBC types. If DSN Option JDConv is enabled, it'll also parse floating point julianday values (whether provided as float or a string of a float) into ODBC types and when writing it'll write floating point into database.
If you can afford to change the schema, you can add a generated virtual column. This is cheap in storage, because data is not affected, but it costs when you query the column. This column can calculate other column into the values and decltypes you need for ODBC.
ALTER TABLE data ADD COLUMN
Datepart date AS (date(LastModifiedDate))
Then to get the Datepart, you simply query the column.
SELECT Datepart FROM data
i want to get all entries from a SQLite table, which have the timestamp from the same month.
For example, the user can type in "July" and then i want to get all entries made in the 7. month.
The current "time"-column is a simple string and in the Format (DD.MM.YYYY HH:MM:SS)
Is there a way to do this with SQLite or will i need to use code in my program?
Assuming that your time strings have a fixed length, you could use a query like this:
SELECT * FROM MyTable WHERE time LIKE '__.07%';
However, you should always stored dates in one of the supported date/time formats so that you are able to use the built-int date/time functions.
I use sqlite3 C/C++ API to retrieve rows from a table using SELECT query. I don't see any sqlite3_column_timestamp() to retrieve a timestamp column value after sqlite3_step().. How to get timestamp values ?
SQLite does not have a special timestamp data type.
When you want to use any of SQLite's date and time functions, you have to store timestamps in one of the formats supported by them, i.e., a string like YYYY-MM-DD HH:MM:SS or HH:MM:SS, a julian date number, or a Unix timestamp number.
You can declare a table column type as DATETIME, but SQLite will just ignore that type; SQLite always allows to put values of any type in any column. Such a declaration would be useful only as documentation.
The column/value accessors will only have types corresponding to the data types they support directly (NULL, INTEGER, REAL, TEXT, BLOB).
You would use the TEXT access to get/set the column value of dates.
There are some helper functions within SQL that they provide that let you to handle them in your queries.
I am not familiar with SQLite Manager, but I would assume that it is only reporting the data type that the table was declared with.
When parsing CREATE statements, sqlite understands the intention of many well supported datatypes and automatically maps them to what is appropriate for its internal storage structure. VARCHAR would be mapped to TEXT, for instance. I assume the column was declared DATETIME and sqlite just internally mapped it to TEXT.
Following are the datetime values stored in a table as varchar. I want to convert them into datetime while using it in SELECT sql.
8/14/2012 7:52:32 AM
8/16/2012 3:34:22 AM
8/14/2012 9:04:03 AM
Any idea?
SQLite doesn't support a native datetime data type.
SQLite does not have a storage class set aside for storing dates
and/or times. Instead, the built-in Date And Time Functions of SQLite
are capable of storing dates and times as TEXT, REAL, or INTEGER
values:
You can get your output in the format you want with strftime() or datetime().
This is easy, but I can't figure it out from the SQLite FAQ and vignette for ALTER TABLE.
I have a date column, but to find a time difference, I need to use julian dates, so I feel like I might as well add a julian date column because I'll be doing this a lot. But I can't figure out how to do it.
I've gone through a bunch of iterations, but I don't think I'm clicking with the SQLite philosophy of the ALTER TABLE and INSERT INTO commands. Thanks!
But I have no idea how to permanently
add a column to a table that is a
function of other columns in that
table. Is this not common usage?
You can't add a calculated column in an SQLite table. But you can do that with a VIEW.
CREATE TABLE TableWithDates (
ID INTEGER PRIMARY KEY,
Iso8601 TEXT
);
CREATE VIEW ViewWithDates AS
SELECT ID, Iso8601, JULIANDAY(Iso8601) AS Julian
FROM TableWithDates;
sqlite> INSERT INTO TableWithDates VALUES (1, CURRENT_TIMESTAMP);
sqlite> SELECT * FROM TableWithDates;
1|2010-12-23 21:13:26
sqlite> SELECT * FROM ViewWithDates;
1|2010-12-23 21:13:26|2455554.3843287
There are no DATE or TIME types in Sqlite. You're free to select what makes sense for you. If it's just timestamps for logging or something, STRING should be ok. If you're going to do datetime comparisons and math (which you are according to the question), INTEGER would be best.
This page discuses built-in functions for use. If you use INTEGER to store seconds since epoch, you can use subtraction to find a time difference.