I simply want to show a date and its day of the week from a table.
The following works:
select "invDate", (select extract (dow from timestamp '2014-09-22'))
from "tblInvMaster"
But the moment I try to use the actual field like the example below, it doesn't work:
select "invDate", (select extract (dow from timestamp "invDate"))
from "tblInvMaster"
The above gives a syntax error where the field name starts in timestamp.
What is the correct method of getting this to work?
The syntax
TYPENAME 'VALUE'
e.g.
TIMESTAMP '2014-01-01'
is only valid in SQL for type literals.
If you want to cast a non-literal value you must use an explicit cast. Most likely you don't require a cast at all, and can just write:
extract(dow from "invDate")
as "invDate" should already be a timestamp or date. If it isn't, you'll need to CAST("invDate" AS timestamp).
Related
With mysql it is possible to search for a full month with a sql query like
select * from table where date_created >= '2020-12-01' and date_created <= '2020-12-32'
column date_created is datetime type.
This does not work with mariadb. I know that the date 2020-12-32 is invalid. But is it possible to get this working with mariadb?
There is no way to make this statement work without modifying either your code or your table definition:
Since the date_created is defined as date type, the strings in the where clause will be converted to date before doing comparison. The date "2020-12-32" is invalid and will be converted to "0000-00-00" which means the where condition becomes WHERE date_created > 2020-12-01 and date_created < 0000-00-00: therefore the statement will not return any rows.
However it is interesting that the optimizer doesn't figure out an impossible WHERE condition and is doing a scan.
I'm new to the SQL world and im going crazy trying to figure out how to SELECT date from a datetime field in SQLITE.
Example: value <11/11/2005 14:56>, i just want to select <11/11/2005> for EVERY ROW.
I tried strftime(), date(), CAST() and other functions but the output its always NULL.
For example i tried querying SELECT strftime('%d/%m/%Y' , columnname) AS date FROM tablename;
OUTPUT: "NULL" in every row
Can someone help me understand what im doing wrong and how can i fix it? Thank you!!!
It always returns NULL because MM/DD/YYYY is not a valid sqlite date format. Treat the column as a string and use substr and instr to drop off the time portion. Something like (no guarantees, check the doc!)
SELECT substr(columname,0,instr(columnname,' '))
Re comment "how to order by the date in descending order"
This problem is a good argument (the best argument?) for storing the date in a sqlite date/time format. There is a strategy in this post for converting MM/DD/YYYY to YYYY-MM-DD (which sorts dates correctly).
If it's not too late, it would be advisable to change the date storage to a valid sqlite date format. strftime can be used to present the date as desired, and sorting will be accurate.
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.