DATEVALUE
引用符で囲まれたテキストの内部日付番号を返します。
内部日付番号を数字として返します。数字は、Collabora Office が日付を計算するために使用する日付システムによって決定されます。
もし、テキスト文字列が時間を含んでいるなら、DATEVALUE 関数は変換の整数部分を返すだけです。
This function is part of the Open Document Format for Office Applications (OpenDocument) standard Version 1.2. (ISO/IEC 26300:2-2015)
DATEVALUE("日付文字列")
テキスト は有効な日付の表現であり、引用符で囲む必要があります。
When entering dates as part of formulas, slashes or dashes used as date separators are interpreted as arithmetic operators. Therefore, dates entered in this format are not recognized as dates and result in erroneous calculations. To keep dates from being interpreted as parts of formulas use the DATE function, for example, DATE(1954;7;20), or place the date in quotation marks and use the ISO 8601 notation, for example, "1954-07-20". Avoid using locale dependent date formats such as "07/20/54", the calculation may produce errors if the document is loaded under different locale settings.
Unambiguous conversion is possible for ISO 8601 dates and times in their extended formats with separators. If a #VALUE! error occurs, then unselect Generate #VALUE! error in Collabora Office - PreferencesTools - Options - Collabora Office Calc - Formula, button Details... in section "Detailed Calculation Settings", Conversion from text to number list box.
=DATEVALUE("1954-07-20") yields 19925.