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Overview
| Comment: | Clarification of the automatic conversion rules for inserting TEXT into a NUMERIC column. |
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| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA3-256: |
9840457b31a319ae22ea111b962f6fbf |
| User & Date: | drh 2019-10-14 00:20:55 |
Context
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2019-10-14
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| 00:26 | Further clarification of automatic affinity conversion rules. check-in: 3a3335a61e user: drh tags: trunk | |
| 00:20 | Clarification of the automatic conversion rules for inserting TEXT into a NUMERIC column. check-in: 9840457b31 user: drh tags: trunk | |
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2019-10-11
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| 03:26 | Version 3.30.1 check-in: bb0f52c956 user: drh tags: trunk | |
Changes
Changes to pages/datatype3.in.
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<p>^A column with TEXT affinity stores all data using storage classes NULL, TEXT or BLOB. ^If numerical data is inserted into a column with TEXT affinity it is converted into text form before being stored.</p> <p>^A column with NUMERIC affinity may contain values using all five storage classes. ^When text data is inserted into a NUMERIC column, the storage class of the text is converted to INTEGER or REAL (in order of preference) if such conversion is lossless and reversible. ^For conversions between TEXT and REAL storage classes, SQLite considers the conversion to be lossless and reversible if the first 15 significant decimal digits of the number are preserved. ^If the lossless conversion of TEXT to INTEGER or REAL is not possible then the value is stored using the TEXT storage class. ^No attempt is made to convert NULL or BLOB values.</p> <p>^A string might look like a floating-point literal with a decimal point and/or exponent notation but as long as the value can be expressed as an integer, the NUMERIC affinity will convert it into an integer. ^(Hence, the string '3.0e+5' is stored in a column with NUMERIC affinity as the integer 300000, not as the floating point value 300000.0.)^</p> |
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<p>^A column with TEXT affinity stores all data using storage classes NULL, TEXT or BLOB. ^If numerical data is inserted into a column with TEXT affinity it is converted into text form before being stored.</p> <p>^A column with NUMERIC affinity may contain values using all five storage classes. ^When text data is inserted into a NUMERIC column, the storage class of the text is converted to INTEGER or REAL (in order of preference) if the text is a well-formed integer or real literal, respectively. ^If the TEXT value is a well-formed integer literal that is too large to fit in a 64-bit signed integer, it is converted to REAL. ^For conversions between TEXT and REAL storage classes, only the first 15 significant decimal digits of the number are preserved. ^If the TEXT value is not a well-formed integer or real literal, then the value is stored as TEXT. ^(For the purposes of this paragraph, hexadecimal integer literals are not considered well-formed and are stored as TEXT. (This is done for historical compatibility with versions of SQLite prior to [version 3.8.6] [dateof:3.8.6] where hexadecimal integer literals were first introduced into SQLite.))^ ^No attempt is made to convert NULL or BLOB values.</p> <p>^A string might look like a floating-point literal with a decimal point and/or exponent notation but as long as the value can be expressed as an integer, the NUMERIC affinity will convert it into an integer. ^(Hence, the string '3.0e+5' is stored in a column with NUMERIC affinity as the integer 300000, not as the floating point value 300000.0.)^</p> |