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91 lines
5.0 KiB
91 lines
5.0 KiB
Note: these types are modeled after the MySQL data types (which seemed the broadest
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and closest to ANSI standard). I include these notes for reference only - they are
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for determining how types will be converted..(todo)
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TINYINT - A very small integer that can be signed or unsigned. If signed, the
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allowable range is from -128 to 127. If unsigned, the allowable range is from 0
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to 255. You can specify a width of up to 4 digits.
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SMALLINT - A small integer that can be signed or unsigned. If signed, the
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allowable range is from -32768 to 32767. If unsigned, the allowable range is
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from 0 to 65535. You can specify a width of up to 5 digits.
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MEDIUMINT - A medium-sized integer that can be signed or unsigned. If signed,
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the allowable range is from -8388608 to 8388607. If unsigned, the allowable
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range is from 0 to 16777215. You can specify a width of up to 9 digits.
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INT - A normal-sized integer that can be signed or unsigned. If signed, the
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allowable range is from -2147483648 to 2147483647. If unsigned, the allowable
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range is from 0 to 4294967295. You can specify a width of up to 11 digits.
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BIGINT - A large integer that can be signed or unsigned. If signed, the
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allowable range is from -9223372036854775808 to 9223372036854775807. If
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unsigned, the allowable range is from 0 to 18446744073709551615. You can specify
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a width of up to 11 digits.
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FLOAT(M,D) - A floating-point number that cannot be unsigned. You can define the
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display length (M) and the number of decimals (D). This is not required and will
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default to 10,2, where 2 is the number of decimals and 10 is the total number of
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digits (including decimals). Decimal precision can go to 24 places for a FLOAT.
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DOUBLE(M,D) - A double precision floating-point number that cannot be unsigned.
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You can define the display length (M) and the number of decimals (D). This is
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not required and will default to 16,4, where 4 is the number of decimals.
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Decimal precision can go to 53 places for a DOUBLE. REAL is a synonym for
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DOUBLE.
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DECIMAL(M,D) - An unpacked floating-point number that cannot be unsigned. In
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unpacked decimals, each decimal corresponds to one byte. Defining the display
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length (M) and the number of decimals (D) is required. NUMERIC is a synonym for
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DECIMAL.
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Date and Time Types:
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DATE - A date in YYYY-MM-DD format, between 1000-01-01 and 9999-12-31. For
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example, December 30th, 1973 would be stored as 1973-12-30.
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DATETIME - A date and time combination in YYYY-MM-DD HH:MM:SS format, between
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1000-01-01 00:00:00 and 9999-12-31 23:59:59. For example, 3:30 in the afternoon
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on December 30th, 1973 would be stored as 1973-12-30 15:30:00.
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TIMESTAMP - A timestamp between midnight, January 1, 1970 and sometime in 2037.
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This looks like the previous DATETIME format, only without the hyphens between
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numbers; 3:30 in the afternoon on December 30th, 1973 would be stored as
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19731230153000 ( YYYYMMDDHHMMSS ).
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TIME - Stores the time in HH:MM:SS format.
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YEAR(M) - Stores a year in 2-digit or 4-digit format. If the length is specified
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as 2 (for example YEAR(2)), YEAR can be 1970 to 2069 (70 to 69). If the length
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is specified as 4, YEAR can be 1901 to 2155. The default length is 4.
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String Types:
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CHAR(M) - A fixed-length string between 1 and 255 characters in length (for
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example CHAR(5)), right-padded with spaces to the specified length when stored.
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Defining a length is not required, but the default is 1.
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VARCHAR(M) - A variable-length string between 1 and 255 characters in length;
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for example VARCHAR(25). You must define a length when creating a VARCHAR field.
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BLOB or TEXT - A field with a maximum length of 65535 characters. BLOBs are
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"Binary Large Objects" and are used to store large amounts of binary data, such
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as images or other types of files. Fields defined as TEXT also hold large
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amounts of data; the difference between the two is that sorts and comparisons on
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stored data are case sensitive on BLOBs and are not case sensitive in TEXT
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fields. You do not specify a length with BLOB or TEXT.
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TINYBLOB or TINYTEXT - A BLOB or TEXT column with a maximum length of 255
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characters. You do not specify a length with TINYBLOB or TINYTEXT.
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MEDIUMBLOB or MEDIUMTEXT - A BLOB or TEXT column with a maximum length of
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16777215 characters. You do not specify a length with MEDIUMBLOB or MEDIUMTEXT.
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LONGBLOB or LONGTEXT - A BLOB or TEXT column with a maximum length of 4294967295
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characters. You do not specify a length with LONGBLOB or LONGTEXT.
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ENUM - An enumeration, which is a fancy term for list. When defining an ENUM,
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you are creating a list of items from which the value must be selected (or it
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can be NULL). For example, if you wanted your field to contain "A" or "B" or
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"C", you would define your ENUM as ENUM ('A', 'B', 'C') and only those values
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(or NULL) could ever populate that field.
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